Nutrition and physical activity

Consuming a wide variety of nutritious foods during pregnancy is important to ensure that the nutritional requirements of both mother and baby are met. While supplementation of vitamins and minerals is common during pregnancy, only some supplements are beneficial. Regular physical activity has health benefits for mother and baby and is safe.

11.1 Nutrition

The nutritional status of a woman before and during pregnancy plays a vital role in fetal growth and development. The basic principles of healthy eating remain the same, though requirements for some nutrients (eg iron, folic acid) may increase.

11.1.1 Background

Knowledge about healthy eating during pregnancy

Observational studies carried out in Australia have found:

• low levels of awareness of dietary guidelines during pregnancy among women (Bookari et al 2016); (Lee et al 2016)
• low levels of women meeting dietary recommendations for the five food groups (Mishra et al 2015); (Malek et al 2016b); (Bookari et al 2017); (Lee et al 2018a)
• low levels of knowledge of foods to avoid during pregnancy (Bryant et al 2017)
• limited dietary counselling by health professionals (Lee et al 2016); (Lee et al 2018b).

An Irish cohort study (McGowan & McAuliffe 2013) found that women with a 'health conscious' dietary pattern were older, had a higher level of education and had a lower BMI than those with an 'unhealthy' dietary pattern. A study in New Zealand also found that a ‘health conscious’ dietary pattern was associated with increasing age, better self-rated health, lower pre-pregnancy BMI and not smoking (Wall et al 2016).

Access to healthy food

• Geographical location: The decreased availability and affordability of nutritious foods (such as fresh fruit and vegetables and wholegrain bread), especially in remote and regional areas in Australia has been described frequently. The cost of nutritious foods in these areas can be over 30% higher than in major cities and may affect food purchases NHMRC 2000; NT DHCS 2007; (Harrison et al 2010); (Landrigan & Pollard 2011).
• Socioeconomic status: In some urban centres, people in lower socioeconomic groups have less access to supermarkets and greater access to fast food outlets than more advantaged groups (Burns & Inglis 2007), (Ball et al 2009). Supermarkets generally offer a wider variety of food products, as well as fresh raw food.
• Migrant and refugee women: Following migration, food habits may change out of choice, because of the limited availability of traditional and familiar foods, or because of change in economic circumstances in Australia. Similarly, financial and language difficulties may affect access to education and employment opportunities which then affects income, health and nutrition literacy, and access to nutritious foods. Some migrants experience disadvantages such as social isolation and poor housing, which can affect access to safe food and safe preparation of food, and are generally in a relatively vulnerable position in their new environments, regardless of the type of migration WHO 2010.

11.1.2 Discussing nutrition

Australian dietary guidelines for pregnant women

As outlined in the Australian Dietary Guidelines NHMRC 2013, consuming a variety of nutritious foods is particularly important during pregnancy and breastfeeding.

• Vegetables, legumes/beans and fruit: consumption of vegetables and fruit before and during pregnancy make important contributions to health outcomes for women and their children.
• Grain (cereal) foods: wholegrain foods are a valuable source of iron and zinc and fibre. Most bread in Australia is fortified with folic acid and made with iodised salt.
• Lean meats and poultry, fish, eggs, tofu, nuts and seeds, and legumes/beans: lean red meat and chicken are good sources of protein, iron and zinc. Maternal consumption of fish during pregnancy is likely to have a range of health benefits for women and their children but the fish should be low in mercury (see Table C2). Nuts, seeds and legumes/beans are important foods for people who choose vegetarian or vegan dietary patterns and meals without meat, as they can provide an alternative source of nutrients. For several nutrients, including iron, calcium and vitamin B₁₂, care needs to be taken to include a variety of alternatives if animal foods are excluded.
• Milk, yoghurt and cheese and/or their alternatives: milk, yoghurt and cheese or their alternatives are good sources of calcium.
• Water: pregnant women require more water to support fetal circulation, amniotic fluid and a higher blood volume — fluid need is 750–1,000 mL a day above the estimated daily intake of 2.1 L.
• Foods containing saturated fat, added salt, added sugars: intake of these foods should be limited in general and during pregnancy. The additional energy requirements of pregnancy should be met through additional serves of foods from the five food groups rather than energy-dense foods.
• Alcohol: not drinking alcohol is the safest option during pregnancy (see Chapter 13).

Table C1 outlines the recommended number of serves of different food groups during pregnancy. However, it is acknowledged that dietary patterns may vary depending on cultural background. 

Table C2: Foods to be consumed with caution during pregnancy

• Due to the risk of listeriosis, pre-prepared or pre-packaged cut fruit or vegetables should be cooked. Pre-prepared salad vegetables (eg from salad bars, including fruit salads and cut melon) should be avoided 

• Raw or undercooked meat, chilled pre-cooked meats, and pâté and meat spreads should be avoided during pregnancy due to risk of listeriosis 

• Care needs to be taken with consumption of some fish species (eg shark/flake, marlin or broadbill/swordfish, orange roughy and catfish) due to the potentially higher mercury content 

• Foods containing raw eggs should be avoided due to the risk of salmonella 

• Unpasteurised dairy products and soft, semi-soft and surface-ripened cheese should be avoided due to the risk of listeriosis 

• Sugar-sweetened drinks are associated with dental conditions, such as caries 

• Food Standards Australia and New Zealand suggests limiting intake during pregnancy to 200 mg/day of caffeine FSANZ 2019, noting that caffeine is present in coffee (145 mg/50 mL espresso; 80 mg/250 mL instant coffee), tea (50 mg/220 mL), colas (36 mg/375 mL), energy drinks (80 mg/250 mL) and chocolate (10 mg/50g). 

Source: NHMRC 2013; FSANZ 2019. 

Recent evidence on dietary patterns 

Dietary patterns associated with healthy outcomes generally have high intake of fruits, vegetables, legumes, wholegrains, fish, seafood, lean meats, low-fat dairy and water. Dietary patterns associated with poorer outcomes include those high in sweetened foods and beverages, foods high in saturated fats (eg fried foods), red and processed meats and refined grains.  

A healthy dietary pattern can help reduce the risk of: 

• excessive gestational weight gain (Ramson et al 2020)

• gestational diabetes (Martin et al 2016); (Schoenaker et al 2016); (Assaf-Balut et al 2017); Zareei et al 2018; (Pham et al 2019) 

• gestational hypertension (Schoenaker et al 2014); (Gresham et al 2016); (Ikem et al 2019)

• antenatal depression (Miyake et al 2018). 

Conversely, an unhealthy dietary pattern may increase the risk of gestational diabetes (Shin et al 2015); (Flynn et al 2016) and antenatal depression Baskin et al 2017. 

The evidence is inconsistent on the association between dietary pattern in pregnancy and: 

• preterm birth (Englund-Ogge et al 2014); (Rasmussen et al 2014); (Saunders et al 2014); (Smith et al 2015); (Assaf-Balut et al 2017); (Assaf-Balut et al 2018); (Chia et al 2018); (Chia et al 2019); (Raghavan et al 2019))

• fetal growth (Martin et al 2015); (Flynn et al 2016); (Gresham et al 2016); (Assaf-Balut et al 2017); (Chia et al 2018); (Emond et al 2018); Martínez-Galiano et al 2018; (Assaf-Balut et al 2019); (Chia et al 2019); (Englund-Ogge et al 2019) 

• childhood growth van den Broek et al 2015; (Fernandez-Barres et al 2016); (Chatzi et al 2017); (Fernandez-Barres et al 2019)

• childhood cardiometabolic health (Fernandez-Barres et al 2016); (Chatzi et al 2017); (Leermakers et al 2017)  

• childhood wheeze (Castro-Rodriguez et al 2016); (Alvarez Zallo et al 2018); (Zhang et al 2019). 

Systematic reviews into vegan-vegetarian diets found inconsistency in results on birthweight, similar duration of pregnancy between vegan-vegetarian and omnivorous diets and a suggestion of risk of iron, vitamin B12 (Piccoli et al 2015) and zinc deficiency (Foster et al 2015); (Piccoli et al 2015) with vegan-vegetarian diets. 

A systematic review found that fasting during Ramadan among well-nourished women did not increase the risk of preterm birth or low birthweight (Glazier et al 2018). 

Recent evidence on consumption of specific foods/food categories during pregnancy 

The systematic review conducted to inform development of these Guidelines (Ramson et al 2020) found that the recent evidence on specific foods or food categories that should be promoted or avoided during pregnancy was generally observational but was consistent with the findings on dietary patterns.  

Fruit, vegetables and legumes 

There is evidence from observational studies that eating vegetables, fruit and legumes during pregnancy is beneficial to both mother and baby, with 

• a reduction in risk of neural tube defects (OR 0.32; 95%CI 0.14 to 0.71; n=918) (Wang et al 2015a) 

• possible associations with improvements in glucose tolerance (p<0.05; n=180) (Soto et al 2015), fetal growth (aOR 0.63; 95%CI 0.40 to 0.98; n=1,036) (Martinez-Galiano et al 2018), pre-eclampsia (aRR 0.20; 95%CI 0.04 to 0.98; p for trend=0.041; n=987) (Torjusen et al 2014); (Mi et al 2019), preterm birth (OR 0.67; 95%CI 0.50 to 0.91; n=923) (Smith et al 2015); (Chia et al 2016) and wheeze at 12 months (OR: 0.44; 95%CI 0.20 to 0.99; n=1,087) (Alvarez Zallo et al 2018).  

Low fruit intake is associated with higher prevalence of major depressive disorder (PR 1.43, 95%CI 1.04 to 1.95; n=712) and low intake of legumes is associated with generalised anxiety disorder (PR 1.40, 95%CI 1.01 to 1.93; n=712) (n=712) (Paskulin et al 2017). A lower risk of childhood leukaemia is associated with maternal consumption of fruit (OR: 0.81, 95% CI: 0.67 to 0.99), vegetables (OR: 0.51, 95% CI: 0.28 to 0.94) and legumes (OR 0.76, 95% CI: 0.62 to 0.94) (n=903) (Dessypris et al 2017). Total daily fruit and vegetable consumption during pregnancy does not appear to be associated with maternal sleep duration (ß -0.03; 95%CI -0.07 to 0.00; n=2,951) (Duke et al 2017). 

Dairy 

There is evidence from observational studies that higher maternal intake of all dairy products (255 vs 32 g/day) is associated with a reduced risk of eczema in babies (aOR 0.64; 95%CI 0.42 to 0.98) (Miyake et al 2015). Maternal milk intake is associated with reduced risk of neural tube defects (1-2 vs <1 time/week; OR 0.50; 95%CI 0.28 to 0.88; n=918) (Wang et al 2015a), asthma (OR 0.83; 95% CI 0.69 to 0.99; n=1,227), allergic rhinitis (OR 0.85; 95%CI 0.74 to 0.97; n=1,227) (Bunyavanich et al 2014) and cow’s milk allergy in children (OR 0.56, 95%CI 0.37 to 0.86; p<0.01; n=6,288) (Tuokkola et al 2016). Higher yoghurt intake (80 g vs 4 g a day) is associated with lower prevalence of depressive symptoms during pregnancy (aOR 0.69; 95%CI 0.48 to 0.99, p for trend 0.03; n=1,745) (Miyake et al 2015).  

Potential allergens 

There is evidence from observational studies that a lower risk of peanut allergy in the infant is associated with maternal peanut consumption during the first trimester (OR 0.53; 95%CI 0.30 to 0.94; n=1,227) (Bunyavanich et al 2014) or pre-pregnancy and during pregnancy (≥5 times vs <1 time per month: OR 0.31; 95% CI 0.13 to 0.75; P(trend)=0.004; n=8,205) (Frazier et al 2014). Maternal wheat intake during the second trimester may reduce atopic dermatitis in the infant (OR 0.64; 95%CI 0.46 to 0.90; n=1,227) (Bunyavanich et al 2014). 

Meat 

There is evidence from observational studies that lower maternal meat consumption may be protective against wheeze in the child (p=0.039; n=1,000) (Castro-Rodriguez et al 2016) but that maternal intake of cured meats may be associated with a risk of childhood retinoblastoma (OR 5.07, 95 % CI 1.63 to 15.70; n=199) (Lombardi et al 2015). 

Fish 

There is evidence from systematic reviews of observational studies that maternal fish intake may be associated with positive neurodevelopmental outcomes (qualitative review; 8 studies) (Starling et al 2015) and a reduced risk of childhood leukaemia (OR 0.27, 95% CI: 0.14 to 0.53; 2 studies) (Dessypris et al 2017). It does not appear to affect the risk of infant eczema (RR 0.88; 95%CI 0.75 to 1.04; 10 studies), wheeze (RR 0.94; 95%CI 0.83 to 1.07; 8 studies), allergic rhinitis (RR 0.95; 95%CI 0.62 to 1.45; 3 studies) or asthma (RR 0.94; 95%CI 0.75 to 1.18; 4 studies) (Zhang et al 2017).  

Observational studies have found positive associations between maternal seafood intake during pregnancy and language and communication scales in the infant (n=38,351) (Vejrup et al 2018) and metabolic health of children (β = -0.96; 95%CI -1.49 to -0.42; n=805) (Stratakis et al 2020) but were inconsistent regarding the effect on child growth (Stratakis et al 2016); van den Berg et al 2016. 

There is evidence from observational studies that low intake of seafood may be associated with increased risk of antenatal depression (aOR 1.54; 95%CI 1.25 to 1.89; n=12,418) (Emmett et al 2015).  

A cohort study (n=3,279) (Mohanty et al 2016) found a possible association between lean fish intake and preterm birth (RR 1.55; 95% CI 1.04 to 2.30). The study noted that studies of mechanisms and potential contributing factors (including seafood preparation and nutrient contaminant content) are warranted. There was no association between fatty fish intake and preterm birth and no association between other pregnancy complications and either lean or fatty fish consumption.  

While fish consumption during pregnancy may have benefits for the women and child, high fetal exposure to mercury through maternal fish consumption is associated with low birthweight (MD -34 g; 95%CI -46 g to -22 g; n=56,988) and small-for-gestational age (aOR 1.19; 95%CI 1.08 to 1.30; n=56,988) (Vejrup et al 2014), delayed language and communication skills in a generally low exposed population (n=46,750 mother-child pairs) (Vejrup et al 2016) and an unfavourable metabolic profile in children (β per 2-fold increase in mercury concentration 0.18; 95% CI 0.01 to 0.34) (Stratakis et al 2020). Types of fish that should be avoided during pregnancy due to potential high mercury content are listed in Table C2. 

Carbohydrates 

There is evidence from secondary analysis of RCT participants that, in obese women with impaired glucose tolerance, a lower carbohydrate intake in late pregnancy is associated with a lower fat mass in the baby at birth (188 vs 238 g/day; ptrend=0.006; n=222) (Renault et al 2015a). There is evidence from cohort studies that high maternal carbohydrate consumption may be associated with increases in birthweight (4g for each additional 10 g/day; 95%CI 1.0 to 7.0; p=0.003; n=1,196) (Sharma et al 2018) and with infant wheeze (potatoes once or twice a week OR 1.75; 95%CI 1.22 to 2.51; n=1,087; pasta never or occasionally; p=0.049) (Castro-Rodriguez et al 2016); (Alvarez Zallo et al 2018). 

Protein 

There is evidence from observational studies that maternal protein intake may be associated with a higher risk of gestational diabetes (OR highest vs lowest quartile of intake 2.15; 95% CI 1.27 to 3.62; p=0.016; n=980) (Pang et al 2017), may increase fat-free mass in the infant (ß 0.14; 95 % CI 0.03 to 0.25 for highest vs lowest quartile of intake; n=2,694 mother-child pairs) Tielemans et al 2017, may reduce newborn abdominal adipose tissue (-0.18 mL; 95%CI -0.35 to -0.001 mL per 1% protein-to-carbohydrate substitution and -0.25 mL; 95%CI 0.46 to -0.04 mL per 1% protein-to-fat substitution; n=320 mother-child pairs) (Chen et al 2016) and may reduce early length growth (0.09 cm/year 6 months to late childhood; 95% CI: -0.14 to -0.05; n=1,961) (Switkowski et al 2016). 

Fats 

There is evidence from observational studies that women with uncomplicated pregnancies had lower daily fat intake (32.1%) than women who developed gestational diabetes (36.2%) (p=0.0251; n=55) (Mizgier et al 2019) and that an additional 10 g/day fat intake was associated with a lower birthweight (MD -8 g; 95%CI -16 to -0.3; p=0.04; n=1,196), with the authors concluding that balancing intake of dietary carbohydrate and fat during pregnancy could support optimal birthweight (Sharma et al 2018). 

Sweetened foods and drinks 

There is evidence from secondary analysis of RCT participants that higher consumption of foods and drinks that contribute to intake of added sugars (2 times daily versus <1 time/week) is associated with higher gestational weight gain (MD 5.4 kg; 95% CI 2.1 to 8.7; n=342) (Renault et al 2015b). Observational studies report an association between sugar-sweetened foods and drinks and impaired glucose tolerance (p<0.05; n=180) (Soto et al 2015) and gestational diabetes (aOR for highest vs lowest category 2.03; 95%CI 1.25 to 3.31; n=3,396) (Donazar-Ezcurra et al 2018). It is also associated with an increased prevalence of major depressive disorder (adjusted prevalence ratio [aPR] 1.91; 95%CI 1.19 to 3.07; n=712) (Paskulin et al 2017).  

Fetal and child growth is also affected by higher intake of sweetened foods and drinks, with increased risks of large for gestational age (aRR 1.57; 95%CI 1.05 to 2.35; n=918 mother-child pairs) (Zhu et al 2017), increased infant BMI z score (0.20-unit increase in infant BMI z score; 95% CI 0.02 to 0.38; n=2,686) and overweight at 1 year (aOR 2.19; 95%CI 1.23 to 3.88,686) (Azad et al 2016) and 7 years of age (aRR 1.93; 95%CI 1.24 to 3.01; 918 mother-child pairs) (Zhu et al 2017). Maternal consumption of sweetened foods and beverages is also associated with infant atopy (OR for highest versus lowest quintile of sugar intake 1.38, 95%CI 1.06 to 1.78; per quintile p-trend=0.006; n=8,956) and asthma (OR 2.01, 95% CI 1.23-3.29; per quintile p-trend=0.004 n=8,956) (Bedard et al 2017). 

Fast foods 

There is evidence from cohort studies that ‘fast food’ (eg ready-to-eat food and drinks that are typically higher in energy (kilojoules), low in nutrition and prepared away from home) consumption is associated with an increased risk of gestational diabetes (aOR for high vs low consumption 1.86; 95% CI 1.13 to 3.06; n=3,048) (Dominguez et al 2014), infant eczema (p=0.005; n=1,000) (Castro-Rodriguez et al 2016) and asthma (RR 4.46; 95%CI 1.36 to 14.6; n=1,201 mother-child pairs) (von Ehrenstein et al 2015). A small case-control study found a positive association between maternal intake of fried foods and retinoblastoma in the child (OR 4.89, 95 % CI 1.72 to 13.89; n=299) (Lombardi et al 2015). 

Caffeine 

There is insufficient evidence to confirm or refute the effectiveness of caffeine avoidance on birth weight or other pregnancy outcomes (Jahanfar & Jaafar 2015). Food Standards Australia and New Zealand suggests limiting intake during pregnancy to 200 mg of caffeine FSANZ 2019, noting that caffeine is present in coffee, tea, colas, energy drinks and chocolate. 

There is evidence from observational studies that the risks of preterm birth (OR per 100 mg/d caffeine increase 1.28; 95%CI 1.03 to 1.58; P=0.03; n=858) (Okubo et al 2015) and childhood brain tumours (OR ≥2 cups per day 2.52; 95% CI 1.26 to 5.04; n=1,019) (Greenop et al 2014) increase with caffeine intake.  

11.2 Nutritional supplements

Dietary patterns consistent with the Australian Dietary Guidelines will allow the general population to meet nutrient requirements. However, the recommended dietary intake is higher for some nutrients during pregnancy (NHMRC & NZ Ministry of Health 2020) and supplementation of some nutrients (eg folic acid and iodine) is recommended. Some women may also seek advice on other supplements.  

11.2.1 Vitamins

Pregnancy multivitamins 

Background  

In Australian observational studies: 

• 79% of pregnant women used multivitamin supplements (Shand et al 2016)

• 42% of participants used pregnancy multivitamins, with 26.8% using multivitamins in combination with individual micronutrients and 9.8% using specific micronutrient supplements; nulliparous women were more likely to take supplements (McAlpine et al 2020)

• 83% of women took a multivitamin during pregnancy, with 90% of women with post-secondary education and 64% of women with secondary education only using these supplements (Malek et al 2018)

• pregnancy-specific multivitamin use was reported by 47% of women in the first trimester, 51% in the second trimester and 46% in the third trimester and general multivitamin use was reported by 31% of women in the first trimester, 27% in the second trimester and 35% in the third trimester (Livock et al 2017). 

Summary of recent evidence 

There is very low to low certainty evidence that antenatal multivitamin supplementation among women in high income countries is associated with a reduced risk of small for gestational age (RR 0.77; 95%CI 0.63 to 0.93; 3 cohort studies; very low certainty) and some congenital anomalies and a possible reduced risk of preterm birth (RR 0.84; 95%CI 0.69 to 1.03; 4 cohort studies; very low certainty) (Wolf et al 2017). 

Folic acid (vitamin B9) 

Background 

A survey of pregnant women conducted in Sydney found that 30.6% were taking a supplement of folic acid alone (Shand et al 2016). A cross-sectional study that included national and South Australian cohorts found that, while awareness of recommendations on folic acid supplementation was high (90%), adherence was low (27%) (Malek et al 2016a). 

In an Australian cohort study (Livock et al 2017), 19-46% of women did not meet the recommended daily intake for folate. Conversely, 15-19 % of women consumed beyond the recommended upper limit for folate.  

Dietary sources of folate include green vegetables (eg spinach), legumes, rice, avocado, fruit, beef liver and fortified products (many breakfast cereals, bread, fruit juice, vegemite). 

Summary of the evidence 

There is high certainty evidence that folic acid supplementation ≥400 µg per day preconception and in the first 3 months of pregnancy is associated with a reduction in risk of neural tube defects (RR 0.32; 95%CI 0.17 to 0.60; 4 RCTs; n=6,708) (De-Regil et al 2015). There was no evidence of any preventive or negative effects on other congenital anomalies. 

Evidence from observational studies suggests it may reduce congenital heart defects (RR 0.72; 95%CI 0.63 to 0.82 (Feng et al 2015); OR 0.60; 95%CI 0.49 to 0.71 (Xu et al 2016).  

There is evidence from systematic reviews of observational studies that folic acid supplementation during pregnancy may reduce the risk of acute myeloid leukaemia (OR 0.52; 95%CI 0.31 to 0.89) (Metayer et al 2014), brain and spinal cord tumours in the child (OR 0.77; 95%CI 0.66 to 0.90) Chiavarini et al 2018 and autism spectrum disorders (RR 0.77; 95%CI 0.64 to 0.93, 16 studies) (Wang et al 2017). 

The evidence suggests that folic acid supplementation during pregnancy does not affect the risk of early or late miscarriage (RR 0.97; 95%CI 0.65 to 1.44; 1 RCT; n=903), stillbirth (RR 0.67; 95%CI 0.11 to 4.02; 1 RCT; n=903), total fetal loss (RR 0.95; 95%CI 0.64 to 1.40; 1 RCT; n=903) (Balogun et al 2016), preterm birth (RR 0.99; 95%CI 0.82 to 1.18; 1 RCT; n=1,654 (Saccone & Berghella 2016); RR 1.09; 95%CI 0.77 to 1.54; 1 RCT; n=2,797 (Lassi et al 2013), low birthweight (RR 0.79; 95%CI 0.49 to 1.28; 4 RCT; n=4,453 (Saccone & Berghella 2016); RR 0.80; 95%CI 0.63 to 1.02; 3 studies; n=3,089 (Lassi et al 2013), infant asthma (RR 1.04; 95%CI 0.94 to 1.16; 3 observational studies) or infant wheeze (RR 1.04; 95%CI 0.94 to 1.16; 3 observational studies) (Wang et al 2015b).  

There is inconclusive evidence on the effect of folic acid supplementation on gestational hypertension, pre-eclampsia Hua et al 2016; Bulloch et al 2018; (Liu et al 2018a); Wen et al 2018 and acute lymphoblastic leukaemia in the infant (Metayer et al 2014); (Dessypris et al 2017). 

Other vitamins

• Vitamin B6: There is insufficient evidence to detect clinical benefits in pregnancy (Salam et al 2015), although it appears to be of benefit in reducing nausea (MD in nausea score -3.7; 95%CI -6.9 to -0.5; very low certainty) (Sridharan & Sivaramakrishnan 2018). See also Chapter 54. 

• Vitamin B12: The evidence on vitamin B12 supplementation in pregnancy is of insufficient certainty to draw conclusions. However, it may be of benefit for women with vegetarian or vegan diets, as vitamin B12 is generally not present in plant foods (Pawlak et al 2014). See also Chapter 30. 

• Vitamin C: The evidence does not support routine high dose (1,000 mg/day) vitamin C supplementation for fetal loss (RR 1.28; 95%CI 0.58 to 2.83; 2 RCTs; n=224) (Balogun et al 2016) or perinatal death (RR 0.51; 95%CI 0.05 to 5.54; 1 RCT; n=182) (Rumbold et al 2015b), intrauterine growth restriction (RR 1.56; 95%CI 0.63 to 3.89; 1 RCT; n=159; high certainty), preterm birth (RR 1.06; 95%CI 0.75 to 1.48; 5 RCTs; n=1,685; high certainty) or pre-eclampsia (RR 0.88; 95%CI 0.48 to 1.61; 3 RCTs; n=1,191) (Rumbold et al 2015b). Further research is required to clarify the possible role of vitamin C in the prevention of placental abruption and prelabour rupture of membranes (Rumbold et al 2015b).  

• Vitamin D: Vitamin D supplementation may be a consideration for women with vitamin D levels lower than 50 nmol/L. The evidence for vitamin D supplementation is discussed in Chapter 47. 

• Vitamin E: The evidence on vitamin E supplementation during pregnancy is of insufficient certainty to draw conclusions on efficacy and safety (Fu et al 2018). 

• Vitamins C and E combined: Supplementation with vitamins C and E (500 to 1,000 mg vitamin C plus 400 IU vitamin E) during pregnancy appears to reduce the risk of placental abruption (RR 0.64; 95% CI 0.44 to 0.93, 7 RCTs, n=14,922; high certainty) but increases the risk of term prelabour rupture of the membranes (RR 1.77; 95% CI 1.37 to 2.28, 2 RCTs, n=2,504) (Rumbold et al 2015a). It does not appear to affect other perinatal outcomes (Rumbold et al 2015a); (Balogun et al 2016); (Vahdaninia M. et al 2017); (Fu et al 2018); (Tenorio et al 2018). Combined vitamins C and E may reduce the risk of preterm birth (RR 0.76; 95% CI 0.58 to 0.99) and placental abruption (RR 0.09; 95% CI 0.00 to 0.87) in pregnant women who smoke Abramovici et al 2015. 

• Vitamin A: The evidence does not support vitamin A supplementation for the prevention of fetal loss (RR 1.05; 95%CI 0.90 to 1.23; 3 RCTs; n=52,480) (Balogun et al 2016), maternal mortality (RR 0.88; 95%CI 0.65 to 1.20; 4 RCTs; n=154,039; high certainty), perinatal mortality (RR 1.01; 95%CI 0.95 to 1.07; 1 RCT, n=76,178; high certainty) or preterm birth (RR 0.98; 95%CI 0.94 to 1.01; 5 RCTs, n=48,007; high certainty) (McCauley et al 2015). The evidence on the role of vitamin A supplementation in reducing risk of maternal clinical infection (RR 0.45; 95%CI 0.20 to 0.99; 5 RCTs; n=17,313; low certainty) and preventing anaemia (RR 0.64; 95%CI 0.43 to 0.94; 3 RCTs; n=15,649; moderate certainty) (McCauley et al 2015) may not be generalisable to the Australian context.  

11.2.2 Minerals 

Iron 

Background 

Studies have investigated rates of iron intake, supplementation and iron-deficiency anaemia among Australian women during pregnancy. In a cohort study ((Livock et al 2017)) 68-82% of women did not meet the recommended daily intake level for iron; conversely, 11-24% of women consumed beyond the recommended upper limit for iron. Cross-sectional studies have found that levels of iron-only supplementation are relatively low in general (7-30%) (Chatterjee et al 2016); (Shand et al 2016) and among women with diagnosed iron deficiency (65%) or with diagnosed iron-deficiency anaemia (62%) (Chatterjee et al 2016). 

Studies among Aboriginal and Torres Strait Islander women have found very low levels of women meeting the estimated average requirement for iron in some areas (Lee et al 2018c) and high levels of iron deficiency and anaemia (Leonard et al 2018). 

Iron-rich staple foods include meat, seafood, poultry and wholegrains NHMRC & NZ Ministry of Health 2020. Iron in foods can come in two general forms — as haem or non-haem iron. Iron from animal food sources may be either haem or non-haem whereas the iron in plant sources such grains and vegetables is non-haem NHMRC & NZ Ministry of Health 2020. The haem form is more bioavailable to humans than the non-haem. Absorption is aided by vitamin C and limited by tea and coffee Marsh et al 2009. Where iron-rich foods are not available (eg due to geographical location or socioeconomic factors), women may be at high risk of iron deficiency.  

Summary of the recent evidence 

There is moderate certainty evidence that preventive iron supplementation in pregnancy may reduce the risk of preterm birth (RR 0.93; 95%CI 0.84 to 1.03, 13 RCTs, n=19,286) (Peña-Rosas et al 2015); (Abraha et al 2019).  

There is low certainty evidence that iron supplementation in pregnancy reduces the risk of maternal anaemia at term (RR 0.30; 95%CI 0.19 to 0.46, 14 RCTs, n=2,199 (Peña-Rosas et al 2015); RR 0.38; 95% CI 0.27 to 0.33; 13 RCTs (Abraha et al 2019) and iron deficiency at term (RR 0.43; 95%CI 0.27 to 0.66, 7 RCTs, n=1,256) (Peña-Rosas et al 2015). There is also low certainty evidence that iron supplementation has no clear effect on neonatal death (RR 0.91; 95%CI 0.71 to 1.18, 4 RCTs, n=16,603 (Peña-Rosas et al 2015); RR 0.93; 0.72 to 1.20; 7 RCTs (Abraha et al 2019), low birthweight (RR 0.84; 95%CI 0.69 to 1.03; n=17,613; 11 RCTs (Peña-Rosas et al 2015); RR 0.94, 95% CI 0.79 to 1.13; 7 RCTs (Abraha et al 2019) or congenital anomalies (RR 0.88, 95%CI 0.58 to 1.33, 4 RCTs, n=14,636) (Peña-Rosas et al 2015).  

There is very low certainty evidence that iron supplementation in pregnancy has no clear effect on the risk of maternal death (RR 0.33; 95%CI 0.01 to 8.19, 2 RCTs, n=12,560) (Peña-Rosas et al 2015) or maternal adverse effects (RR 1.29; 95%CI 0.83 to 2.02, 11 RCTs, n=2,423 (Peña-Rosas et al 2015); RR 1.42; 95%CI 0.91 to 2.21; 12 RCTs (Abraha et al 2019). A systematic review indicates that iron supplementation has no clear effect on infant neurodevelopment (MD 0.54 units across different measures; 95% CI -0.67 to 1.75; 3 RCTs) (Jayasinghe et al 2018). 

There is low certainty evidence that weekly (80-300 mg elemental iron) versus daily (30-60 mg elemental iron) supplementation in pregnancy has no clear effect on preterm birth (RR 1.03; 95%CI 0.76 to 1.39; n=1,177; 5 RCTs), birthweight (MD 5.13 g; 95%CI -29.46 to 39.72; n=1,939; 9 RCTs) or low birthweight (RR 0.82; 95%CI 0.55 to 1.22; n=1,898; 8 RCTs) (Pena-Rosas et al 2015).  

There is very low certainty evidence that maternal adverse effects such as constipation and nausea (RR 0.56; 95%CI 0.37 to 0.84; n=1,777; 1 RCT) are reduced with weekly versus daily iron supplementation with no clear effect on the risk of maternal anaemia at term (RR 1.22; 95%CI 0.84 to 1.80; n=676; 4 RCTs), maternal iron-deficiency at term (RR 0.71; 95%CI 0.08 to 6.63; 1 RCT) or neonatal death (RR 0.49; 95%CI 0.04 to 5.42; n=795; 1 RCT) (Pena-Rosas et al 2015). 

There is low certainty evidence that weekly (80-300 mg elemental iron) versus daily (30-60 mg elemental iron) supplementation in pregnancy has no clear effect on preterm birth (RR 1.03; 95%CI 0.76 to 1.39; n=1,177; 5 RCTs), birthweight (MD 5.13 g; 95%CI -29.46 to 39.72; n=1,939; 9 RCTs) or low birthweight (RR 0.82; 95%CI 0.55 to 1.22; n=1,898; 8 RCTs) (Pena-Rosas et al 2015).  

There is very low certainty evidence that maternal adverse effects such as constipation and nausea (RR 0.56; 95%CI 0.37 to 0.84; n=1,777; 1 RCT) are reduced with weekly versus daily iron supplementation with no clear effect on the risk of maternal anaemia at term (RR 1.22; 95%CI 0.84 to 1.80; n=676; 4 RCTs), maternal iron-deficiency at term (RR 0.71; 95%CI 0.08 to 6.63; 1 RCT) or neonatal death (RR 0.49; 95%CI 0.04 to 5.42; n=795; 1 RCT) (Pena-Rosas et al 2015).  

Recommendations for testing and treatment of iron-deficiency anaemia are included in Chapter 30. 

Calcium 

Background 

A survey of pregnant women conducted in Sydney found that 13% were taking a supplement of calcium alone (Shand et al 2016). 

Calcium is found predominantly in milk and milk-based foods, with smaller amounts in bony fish, legumes and most nuts, fortified soy beverages and breakfast cereals (NHMRC & NZ Ministry of Health 2020). 

Calcium requirements during pregnancy are higher among adolescent women than among women older than 18 years (NHMRC & NZ Ministry of Health 2020). 

Summary of recent evidence 

There is consistent evidence from systematic reviews that calcium supplementation reduces the risk of gestational hypertension (Hofmeyr et al 2018); (Sun et al 2019) and pre-eclampsia (Hofmeyr et al 2014); (Khaing et al 2017); (Hofmeyr et al 2018); (Sun et al 2019)).  

High-dose calcium supplementation (≥1 g/day) reduces the risk of gestational hypertension (RR 0.65; 95%CI 0.53 to 0.81; 12 RCTs; n=15,470), with a clearer effect among women with low dietary calcium (RR 0.44; 95%CI 0.28 to 0.70; 7 RCTs; n=10,418) than among women with adequate dietary calcium (RR 0.90; 95%CI 0.81 to 0.99; 4 RCTs; n=5,022) (Hofmeyr et al 2018). High-dose calcium also reduces the risk of pre-eclampsia (RR 0.45; 95CI 0.31 to 0.65; 13 trials; n=15,730; low certainty).  

Low-dose calcium (<1 g/day) also reduces the risk of gestational hypertension (RR 0.57; 95%CI 0.39 to 0.82; 3 RCTs; n=558) (Hofmeyr et al 2018) and pre-eclampsia (RR 0.36; 95%CI 0.23 to 0.57; 4 RCTs; n=980) (Hofmeyr et al 2014). 

A Cochrane review (Hofmeyr et al 2018) found a possible reduction in risk of preterm birth <37 weeks with high-dose calcium among all women (RR 0.76; 95%CI 0.60 to 0.97; 11 trials, n=15,275; low certainty). Another Cochrane review of calcium supplementation trials not specifically targeted at preventing pre-eclampsia (Buppasiri et al 2015) found no clear difference in risk of preterm birth at <37 weeks (RR 0.86; 95% CI 0.70 to 1.05; 13 studies, n=16,139; moderate certainty) or at <34 weeks (RR 1.04; 95%CI 0.80 to 1.36; 4 RCTs, n=5,669; moderate certainty). 

Calcium supplementation does not appear to be of benefit in preventing low birthweight (RR 0.93; 95%CI 0.81 to 1.07; 6 RCTs; n=14,162; moderate certainty) (Buppasiri et al 2015).  

A systematic review found no difference in rates of adverse effects between women taking calcium supplements and those taking a placebo (Buppasiri et al 2015). 

There is some evidence that routine calcium supplementation in pregnancy in high-income countries such as the Netherlands is more cost-effective than selective supplementation (Meertens et al 2018). 

Iodine 

Background 

The NHMRC (2010) Public Statement: Iodine Supplementation for Pregnant and Breastfeeding Women suggests pregnant women take an iodine supplement of 150 µg each day to avoid poor infant neurodevelopment.  

Evidence of iodine deficiency re‐emerged in Australia in the 1990s, motivating mandatory fortification of bread with iodised salt in 2009. The AIHW reports that, while mandatory fortification delivered sufficient amounts of iodine to the general population, intakes for many pregnant and breastfeeding women were insufficient due to their increased requirements AIHW 2016. 

In a review of Australian cohort studies post-fortification (7 studies) (Hurley et al 2019), three studies found that the pregnant women in their studies were iodine replete and four studies found that pregnant women were in the mild-to-moderate iodine deficiency category. Only two studies documented iodine sufficiency among pregnant women in the absence of iodine supplementation.  

A survey of pregnant women conducted in Sydney found that 6.3% were taking an iodine supplement (Shand et al 2016). A study conducted in Gippsland Victoria, a mildly iodine deficient area, found that only 18.9% of participants followed the NHMRC advice, with 42.3% of participants not taking any supplements (or supplements with no iodine or insufficient iodine) Mitchell et al 2018. The remaining women (38.7%) were taking supplements with doses of iodine much higher (200-300 μg) than the NHMRC recommended dose or were taking multiple supplements containing iodine. In a South Australian study, 85.9% women met the estimated average requirement (≥160 μg/day) for iodine intake from food and supplements (Condo et al 2017). When iodine from supplements was excluded, 44.5% of women met the estimated average requirement for iodine intake during pregnancy. In a Western Australian study, 66% of pregnant women were taking iodine supplements (Hine et al 2018). A Tasmanian study (n=255) found that, despite recommendations for iodine supplementation, pregnant Tasmanian women remain at risk of iodine deficiency (Hynes et al 2019). 

An analysis of cross-sectional data from two Australian longitudinal studies pre- and post-fortification of iodine (n=368) (Singh et al 2019) found that the median urinary iodine concentration of pregnant Indigenous women in remote locations remains low and targeted interventions are needed to ensure healthy fetal development. In a cross-sectional study in Western Australia (n=425) (Sherriff et al 2019) ethnicity was associated with iodised salt use, with 76% of Asian women used iodised salt compared with 33% of Caucasian women.  

In a national survey of maternity care providers, while 71% were aware of the NHMRC advice on iodine supplementation, fewer were aware of the recommended dose (38%) or duration (44%), with 73% advising iodine supplements in pregnancy (Guess et al 2017). 

Summary of recent evidence 

There is low certainty evidence that, in settings with mild to moderate iodine deficiency, iodine supplementation may reduce the risk of postpartum hyperthyroidism (average RR 0.32; 95%CI 0.11 to 0.91; three RCTs; n=543 women) with very low certainty evidence of an increased likelihood of gastrointestinal intolerance during pregnancy (average RR 15.33; 95%CI 2.07 to 113.70; one RCT; n=76) (Harding et al 2017). There is low certainty evidence that iodine supplementation has any effects on other outcomes or side effects for mothers or infants (Harding et al 2017); (Farebrother et al 2018).  

RCTs have reported that iodine supplementation: 

• increased maternal urinary iodine levels in areas with iodine deficiency (p<0.05) (Chawanpaiboon 2019) and mild-moderate deficiency (p<0.0001) (Censi et al 2019) 

• decreased maternal thyroglobulin levels (p=0.02) (Censi et al 2019) 

• decreased median neonatal thyroid stimulating hormone levels (p<0.05) (Chawanpaiboon 2019) 

• had no effect on child neurodevelopment at age 5–6 years in mildly iodine-deficient pregnant women (Gowachirapant et al 2017). 

Zinc 

Background 

A survey of pregnant women conducted in Sydney found that 5.6% were taking a zinc supplement (Shand et al 2016). In an Australian cohort study (Livock et al 2017) 17-24% of pregnant women did not meet the recommended daily intake for zinc.  

Summary of recent evidence 

There is some evidence that zinc supplementation may slightly reduce the risk of preterm birth with no clear effect on low birthweight or other outcomes, possibly indicating that low zinc status reflects poorer overall nutrition in some pregnant women (Ota et al 2015); (Liu et al 2018b). Zinc supplementation does not appear to increase or reduce the risk of other outcomes (Nossier et al 2015); Ota et al 2015; Zahiri Sorouri et al 2016; (Oh et al 2020).  

Other minerals 

• There is insufficient high-certainty evidence to show whether dietary magnesium supplementation during pregnancy is beneficial (Makrides et al 2014). 

• There is insufficient evidence to draw conclusions on selenium supplementation in pregnancy (Tara et al 2010); (Rayman et al 2014). 

11.2.2 Other nutritional supplements 

Other multiple micronutrients 

Summary of recent evidence 

There is high certainty evidence from studies conducted in low- to middle-income countries that the use of multiple micronutrients (including iron and folic acid) during pregnancy reduces the risk of low birthweight and may reduce the risk of stillbirth but does not affect the risk of perinatal or neonatal mortality (Keats et al 2019). There is moderate certainty evidence of a reduction in risk of small for gestational age and a possible reduction in risk of preterm birth (<37 weeks) (Keats et al 2019). There is evidence that multiple micronutrient use is associated with a reduction in risk of early preterm birth (<34 weeks), a possible reduction in risk of miscarriage, with no effect on maternal mortality, maternal anaemia, caesarean section or congenital anomalies (Keats et al 2019). These findings may not be generalisable to the Australian context. 

Omega-3 fatty acids 

Background 

Omega-3 fatty acids are found predominantly in oily fish such as mackerel, herrings, sardines, salmon and tuna NHMRC & NZ Ministry of Health 2020. 

In an Australian cross-sectional study, 12% of women took fish oil during pregnancy (Shand et al 2016). 

Summary of the evidence 

There is high certainty evidence that rates of preterm birth <37 weeks (10.1% versus 8.1%%; RR 0.89, 95%CI 0.82 to 0.97; 30 RCTs, n=21,271) and early preterm birth <34 weeks (2.6% vs 1.6%; RR 0.64, 95%CI 0.44 to 0.93; 11 RCTs, n=15,750) are lower in women receiving omega-3 long-chain polyunsaturated fatty acids compared with no omega-3 (Middleton et al 2018). There is moderate-certainty evidence that prolonged pregnancy >42 weeks is probably increased with omega-3 fatty acid supplementation (RR 1.61 95%CI 1.11 to 2.33; n=5,141; 6 RCTs) but insufficient evidence to determine the effect of supplementation on induction post-term (Middleton et al 2018). There is high certainty evidence of a reduced risk of low birthweight (15.6% vs 14%; RR 0.90, 95%CI 0.82 to 0.99; 15 trials, n=8,449;) and moderate certainty evidence for a possible reduced risk of perinatal death (RR 0.75, 95%CI 0.54 to 1.03; 10 RCTs, n=7,416), neonatal care admission (RR 0.92, 95%CI 0.83 to 1.03; 9 RCTs, n=6,920) and a possible small increase in risk of large-for-gestational age babies (RR 1.15, 95%CI 0.97 to 1.36; 6 RCTs, n=3,722) with omega-3 fatty acid supplementation (Middleton et al 2018).  

The large ORIP (Omega-3 fats to Reduce the Incidence of Prematurity) trial (Makrides et al 2019) used a dose of 800 mg docosahexaenoic acid (DHA) and 100 mg eicosapentaenoic acid (EPA) per day. Further analysis of this trial indicates that women with low omega-3 status will benefit most from supplementation with omega-3 (Simmonds et al 2020). 

Probiotics 

A meta-analysis of RCTs conducted to inform these Guidelines (Ramson et al 2020) found low certainty evidence that supplementation with probiotics may be associated with a possible reduction in caesarean section (RR 0.92; 95%CI 0.81 to 1.05; 15 RCTs; n=2,650), and very low certainty evidence of a reduction in Group B streptococcus colonisation (RR 0.76; 95%CI 0.61 to 0.97; n=244) and a possible reduction in risk of gestational diabetes (RR 0.87; 95%CI 0.71 to 1.08; 8 RCTs; n=1,722).  

There is very low or low certainty evidence that probiotic supplementation does not reduce gestational hypertension (RR 1.24; 95%CI 0.74 to 2.06; 4 RCTs; n=955), pre-eclampsia (RR 1.88; 95%CI 0.96 to 3.71; 2 RCTs; n=598), bacterial vaginosis (RR 1.73; 95%CI 0.89 to 3.38; 2 RCTs; n=509), perinatal death (RR 1.17; 95%CI 0.62 to 2.24; 6 RCTs; n=1,670), preterm birth (RR 1.10; 95%CI 0.81 to 1.50; 16 RCTs; n=3,671), small for gestational age (RR 1.04; 95%CI 0.55 to 1.94; 3 RCTs; n=318), large for gestational age (RR 0.95; 95%CI 0.47 to 1.93; 3 RCTs; n=316) or macrosomia (RR 1.06; 0.85 to 1.33; 7 RCTs; n=1,407). 

Herbal preparations 

Background 

An Australian cohort study (n=1,835) found that 34.4% of women were using herbal preparations during pregnancy, of whom 77.9% were self-prescribing these products (Frawley et al 2015). Women were more likely to use herbal medicine if they had anxiety (OR 1.30; 95%CI, 1.02 to 1.64; p=0.031), sleeping problems (OR 1.55; 95%CI 1.15 to 2.11; p=0.005) or fatigue (OR 1.32; 95%CI 1.04 to 1.68; p=0.025) and less likely to use herbal medicine if they had nausea (OR 0.71; 95% CI 0.56 to 0.91; p=0.007). Women who used herbal preparations viewed them as a preventative measure, were looking for something holistic and were concerned about evidence of clinical efficacy when considering the use of these products during pregnancy (Frawley et al 2016).  

Each herbal preparation needs to be considered as a potentially unique therapeutic agent, different in action from any other herbal medicine; even those within the same genus or produced from different parts of the same plant. The use of herbal preparations by pregnant women should be supervised by an appropriately qualified health professional. 

Summary of the evidence 

The evidence on the efficacy and safety of herbal preparations during pregnancy is limited. There is moderate certainty evidence that ginger reduces nausea (MD -4.2 nausea score; 95%CI -6.5 to -1.9), with a low risk of adverse effects (OR 0.4; 95%CI 0.1 to 0.9) (Sridharan & Sivaramakrishnan 2018). There is very low certainty evidence that chamomile is also effective in reducing nausea (MD -4.2; 95%CI -6.7 to -1.7; 1 RCT) (Sridharan & Sivaramakrishnan 2018). There is evidence from a systematic review that garlic may reduce gestational hypertension (RR 0.50; 95%CI 0.25 to 1.00) but does not affect the risk of pre-eclampsia (RR 0.78, 95% CI 0.31 to 1.93) or caesarean section (RR 1.35, 95% CI 0.93 to 1.95), with odour likely to be experienced (RR 8.50, 95%CI 2.07 to 34.88) (Meher & Duley 2006). There is insufficient evidence on the efficacy and safety of echinacea, raspberry leaf, elderberry and St John’s wort during pregnancy (Deligiannidis et al 2014); (Holst et al 2014); (Munoz Balbontin et al 2019).  

11.3 Physical activity 

11.3.1 Background 

Physical activity can be defined as any movement that expends energy. This includes sport, exercise and recreational activities and incidental activity that accrues throughout the day (eg walking to the shops, climbing stairs). 

The Australian Physical Activity and Sedentary Behaviour Guidelines (DoH 2014) recommend that adults aged 18-64 years: 

• accumulate 150 to 300 minutes (2½ to 5 hours) of moderate intensity physical activity or 75 to 150 minutes (1¼ to 2½ hours) of vigorous intensity physical activity, or an equivalent combination of both moderate and vigorous activities, each week 

• do muscle strengthening activities on at least 2 days each week 

• minimise the amount of time spent in prolonged sitting 

• break up long periods of sitting as often as possible. 

Source: ({{DoH 2014}}) 

Levels of physical activity in Australia 

Recent data specific to pregnant women are not available but results from national surveys give some indication of patterns of physical activity and sedentary behaviour.  

In Australia in 2017-18 among 18-64 year olds ABS 2019: 

• the majority (83.5%) engaged in some form of deliberate voluntary exercise (not including workplace physical activity) but only 15.0% of these participants met both the physical activity and muscle strengthening aspects of the guidelines 

• more than half (55.4%) undertook 150 minutes or more of exercise in the last week, excluding workplace physical activity 

• one quarter (24.9%) did strength or toning activities on two or more days in the last week as recommended in the guidelines 

• more than two thirds (69.6%) did not conduct any strength or toning activities.  

An Australian cross-sectional study found that fewer women participated in exercise during pregnancy (61%) compared to before pregnancy (87%) and that they exercised at a significantly lower frequency (p<0.05), intensity (p<0.05) and for a shorter time/duration (p<0.05) (Hayman et al 2016). 

Awareness of and barriers to physical activity among pregnant women 

In a survey of regionally-based Australian women (n=142) (Hayman et al 2019), around half of women (53%) reported receiving advice on exercise as part of antenatal care. However, the advice given was frequently inconsistent with evidence–based guidelines concerning frequency, intensity, duration and benefits and harms. 

Systematic reviews have found that barriers to participating in physical activity were: 

• categorised as intrapersonal (pregnancy-related symptoms and limitations, time constraints, perceptions of already being active, lack of motivation and mother-child safety concerns), interpersonal (lack of advice and information and lack of social support) and environmental, organisational and policy barriers (adverse weather, lack of resources) (Coll et al 2017) 

• predominantly intrapersonal barriers such as fatigue, lack of time and pregnancy discomforts, while enablers included maternal and fetal health benefits (intrapersonal), social support (interpersonal) and pregnancy-specific programs (Harrison et al 2018). 

11.3.2 Discussing physical activity 

Guidelines on physical activity in pregnancy 

The Evidence-based Physical Activity Guidelines for Pregnant Women recommend that (Brown et al 2020): 

• all women without contraindications be encouraged to meet the Australian Physical Activity and Sedentary Behaviour Guidelines (see above) before, during and after pregnancy 

• modifications to physical activity/exercise may be required to accommodate the physical changes that occur as the pregnancy progresses — if there are any concerns (including warning signs and contraindications), women are advised to seek advice from a qualified health professional  

• all pregnant women are advised to do pelvic floor exercises during and after pregnancy  

• health professionals support women to take an active role in shared decision-making about their physical activity/exercise during and after pregnancy.  

Recent evidence on the effects of physical activity during pregnancy 

Physical fitness and quality of life 

There is a possible increase in physical fitness associated with exercise in pregnancy (Hopkins et al 2010); (de Oliveria Melo et al 2012); (Halvorsen et al 2013); (Bisson et al 2015); (Guelfi et al 2016); (Seneviratne et al 2016); (Cai et al 2020) and rates of injury appear to be low (4.1 per 1,000 exercise hours; n=1,469). The evidence on the effect on quality of life suggests an improvement with physical activity (Montoya Arizabaleta et al 2010); (Gustafsson et al 2016); (Haakstad et al 2016); (Prabha et al 2019); (Rodriguez-Blanque et al 2020). Structured exercise interventions reduce the risk of antenatal (RR 0.44; 95%CI 0.32 to 0.61; 6 RCTs; n=798; moderate certainty) and postnatal (RR 0.47; 95%CI 0.34 to 0.65; 5 RCTs; n=1,613; moderate certainty) depression (Ramson et al 2020). 

Effect of physical activity on complications of pregnancy  

The meta-analysis of RCTs conducted to inform the development of these Guidelines (Ramson et al 2020) found that structured exercise interventions during pregnancy were highly beneficial. The interventions mostly involved aerobic (treadmill, stationary cycling, walking, dance, circuit training, swimming) and muscle strengthening exercises (including pelvic floor exercises) for around 60 minutes, three times a week at an intensity of 60-80% of maximum heart rate or 12-14 on the Borg scale and continued to 36 to 39 weeks pregnancy. Compared to women who did not participate in the interventions, participants had lower mean gestational weight gain (MD 0.95 kg; 95%CI -1.20 to -0.69; 29 RCTs; n=5,680; moderate certainty) and were at lower risk of:  

• weight gain exceeding US Institute of Medicine (IOM) recommendations (RR 0.77; 95%CI 0.69 to 0.87; 16 RCTs; n=4,333; low certainty) 

• gestational diabetes (RR 0.74; 95%CI 0.60 to 0.90; 20 RCTs; n=5,592; low certainty) 

• gestational hypertension (RR 0.51; 95%CI 0.37 to 0.71; 7 RCTs; n=3,060; moderate certainty) 

• caesarean section (RR 0.85; 95%CI 0.74 to 0.98; 25 RCTs; n=5,704; moderate certainty)

• macrosomia >4,000 g (RR 0.75; 95%CI 0.59 to 0.96; 15 RCTs; n=4,759; moderate certainty).

Positive impact of physical activity on common conditions in pregnancy 

• Incontinence: Pelvic floor muscle exercises appear to reduce the risk of urinary incontinence in late pregnancy (RR 0.38; 95%CI 0.20 to 0.72; 6 studies; n=624; low quality) and at 3-6 months postpartum (RR 0.71; 95%CI 0.54 to 0.95; 5 studies; n=673; moderate quality) but do not appear to affect the risk of faecal incontinence (RR 0.61; 95%CI 0.30 to 1.25; 2 studies; n=867; moderate quality) (Woodley et al 2017). 

• Glycaemic control: An acute bout of exercise is associated with a decrease in maternal blood glucose from before to during exercise (MD -0.94 mmol/L, 95%CI -1.18 to -0.70;6 studies, n=123) and following exercise (MD 0.57 mmol/L, 95% CI -0.72 to -0.41; n=333) (Davenport et al 2018). 

• Pelvic girdle and low back pain: There is evidence from systematic reviews (Shiri et al 2018); (Davenport et al 2019b), an RCT (Sklempe Kokic et al 2017) and a cohort study (Gjestland et al 2013) that physical activity during pregnancy is associated with a possible reduction in risk of low back (RR 0.91, 95%CI 0.83 to 0.99; 7 studies; n=1,175) and lumbopelvic pain (RR 0.96, 95%CI 0.90 to 1.02; 8 studies; n=1,737) and a reduction in severity of pain during pregnancy (SMD -1.03; 95%CI -1.58 to -0.48; 10 studies; very low to moderate certainty). The evidence on the effect of exercise on pelvic girdle pain and pain in the postpartum period is unclear.  

• Sleep: It is unclear whether moderate to vigorous exercise during pregnancy improves sleep quality Loprinzi et al 2012; (Kocsis et al 2017); (Rodriguez-Blanque et al 2018); (Yang et al 2020) and it is not effective in treating insomnia in pregnancy (Yang et al 2020). 

Effect on labour 

One systematic review (Kramer & McDonald 2006) and eleven RCTs (Salvesen & Morkved 2004); (Baciuk et al 2008); Barakat et al 2008; (Salvesen et al 2014); (Perales et al 2016a); (Perales et al 2016b); (Taniguchi & Sato 2016); (Barakat et al 2018); (Sanda et al 2018); (Rodriguez-Blanque et al 2019a); (Perales et al 2020) reported on duration of labour among women who had participated in a physical activity intervention during pregnancy and those who had not. The systematic review found no clear difference in length of the first (MD 2.00; 95%CI -1.15 to 5.15; 1 study; n=18) or second (MD 5.72; 95%CI -15.22 to 3.78; 1 study; n=18) stage of labour (Kramer & McDonald 2006). With some exceptions, (Salvesen et al 2014); (Perales et al 2016a); (Barakat et al 2018); (Rodriguez-Blanque et al 2019a); (Perales et al 2020), the RCTs found no clear difference in duration of any stage of labour. 

Five RCTs ((Baciuk et al 2008); (Barakat et al 2009); (Salvesen et al 2014); (Taniguchi & Sato 2016); (Sanda et al 2018)) reported on pain relief during labour among women who had participated in a physical activity intervention during pregnancy and those who had not. One study reported fewer requests for analgesia in labour (RR 0.42; 95%CI 0.23 to 0.77; n=71) (Baciuk et al 2008) but there was no clear difference in the other studies. 

Five RCTs (Salvesen & Morkved 2004); (Salvesen et al 2014); (Garnaes et al 2016); (Seneviratne et al 2016); (Rodriguez-Blanque et al 2019b) reported on perineal tears among women who had participated in a physical activity intervention during pregnancy and those who had not. One study found higher rates of intact perineum among the intervention group (aOR 8.57; 95% CI 1.85 to 39.68) (Rodriguez-Blanque et al 2019b) but there was no clear difference in rates of perineal tears in any other study. 

Effect on the infant and child 

There is evidence from systematic reviews that leisure-time exercise during pregnancy is not associated with congenital anomalies (OR 1.23, 95%CI 0.77 to 1.95; 14 studies; n=78,735; very low certainty) (Davenport et al 2019c) and appears to be protective against macrosomia (aOR 0.77; 95%CI 0.61 to 0.96; n=36,896) (Owe et al 2009) and low birthweight, with women who did not exercise before and during pregnancy having an increased risk of very low birthweight (OR 1.75; 95%CI 1.50 to 2.04; n=2,245) (Leiferman & Evenson 2003). Cohort studies suggest a positive association between physical activity during pregnancy and offspring neurodevelopment (4 studies) Nino Cruz et al 2018. Physical activity during pregnancy does not appear to affect childhood weight (n=802) (Kong et al 2016). 

Safety of physical activity during pregnancy 

The evidence did not support an association between: 

• any exercise during pregnancy and: 
  • risk of miscarriage (OR 0.69; 95%CI 0.40 to 1.22; 10 studies) or perinatal mortality (OR 0.79; 95%CI 0.26 to 2.38; 6 studies) (Davenport et al 2019a) 
  • adverse impact on fetal heart rate or uteroplacental blood flow metrics (9 studies; 4,651 women) (Skow et al 2019) 
• vigorous exercise during pregnancy and: 
  • risk of small for gestational age, low birthweight Beetham et al 2019; (Hoffmann et al 2019), large for gestational age or high birthweight (Hoffmann et al 2019) 

  • risk of preterm birth with exercise in the first (OR 0.80; 95%CI 0.48 to 1.35) or second trimester (OR 0.52; 95%CI 0.24 to 1.11; n=1,699) (Evenson et al 2002) 

  • risk of preterm birth with vigorous activity up to 435 min/week (OR 1.2; 95%CI 0.5 to 3.1; n=1,647) (Jukic et al 2012) 

  • risk of post-term birth with exercise in the first (OR 0.93; 95%CI 0.45 to 1.89) or second (OR 1.15; 95%CI 0.47 to 2.79) trimester (n=1,699) (Evenson et al 2002) 

• supine exercise and low birthweight (3 RCTs; very low to low certainty) (Mottola et al 2019)  
• swimming or aqua aerobics and: 
  • risk of miscarriage <22 weeks (19-22 weeks HR 0.9; 95%CI 0.4 to 1.9; n=92,671) (Madsen et al 2007)  
  • risk of spina bifida (aOR 0.68; 95%CI 0.47 to 0.99; n=8,655) (Agopian et al 2013) 
  • significant increase in maternal body temperature (mean increase 0.16±0.35°C; n=109) (Brearley et al 2015). 

A systematic review noted that there was insufficient evidence to ascertain whether maternal exercise in the supine position is safe or should be avoided during pregnancy (Mottola et al 2019). 

Further information about physical activity during pregnancy, including contraindications and signs and symptoms that suggest that physical activity/exercise should be modified, is included in Evidence-based Physical Activity Guidelines for Pregnant Women. 

Recent evidence on the effects of occupational physical activity during pregnancy 

The evidence on risks associated with occupational physical activity during pregnancy is unclear.  

Heavy lifting (eg >200 kg/day) may be associated with an increased risk of pelvic pain (201-500 kg/day: aOR 1.45; 95%CI 1.31 to 1.60; n=50,143) (Larsen et al 2013), stillbirth among women with a previous fetal loss (201-975 kg per day: adjusted hazard ratio [aHR] 2.87; 95%CI 1.37 to 6.01; n=68,086) (Juhl et al 2013) and preterm birth among primigravid women (201-975 kg/day: aHR 1.43; 95%CI 1.13 to 1.80; n=65,530) (Mocevic et al 2014) but does not appear to be associated with small-for-gestational age (Pompeii et al 2005); (Snijder et al 2012); (Juhl et al 2014) or low birthweight ((Snijder et al 2012).  

There is a possible association between occupational standing and increased risk of miscarriage (>6 hours a day: RR 1.16; 95%CI 1.01 to 1.32; 30 studies) or preterm birth (Ritsmitchai et al 1997) (>3 hours per day: OR 1.25; 95%CI 0.99 to 1.57; 11 studies) but no clear difference in small-for-gestational age, birthweight (Eunhee et al 2002) or pelvic pain (Juhl 2005).  

There is insufficient evidence to draw conclusions on strenuous occupational physical exertion in pregnancy but it may be associated with preterm premature rupture of the membranes (OR 1.72; 95%CI 1.16 to 2.56; n=2,929) (Newman et al 2001) and pelvic pain (OR 1.47; 95%CI 1.17 to 1.84; n=2,758) (Juhl 2005). 

11.4 Lifestyle interventions 

The literature review conducted to inform these Guidelines (Ramson et al 2020) analysed the results of randomised controlled trials that compared usual care to: 

• dietary intervention: common themes in dietary advice provided included increasing consumption of fruit and vegetables, protein and fibre and reducing intake of saturated fats, carbohydrates and sugar (eg in soft drinks)  

• exercise intervention: interventions mostly involved aerobic (treadmill, stationary cycling, walking, dance, circuit training, swimming) and muscle strengthening exercises (including pelvic floor exercises) for around 60 minutes, three times a week at an intensity of 60-80% of maximum heart rate or 12-14 on the Borg scale and continued to 36 to 39 weeks pregnancy 

• lifestyle counselling intervention: most interventions involved counselling with a focus on gestational weight gain, diet and exercise with weight gain recommendations based on the US Institute of Medicine (IOM) guidelines and encouraged some form of self-monitoring (eg through weight gain charts, log books, pedometers).  

Mean gestational weight gain was lower among women participating in a dietary intervention (MD -3.76 kg; 95%CI -6.38 to -1.13; 6 RCTs; n=1,432; very low certainty), exercise intervention (MD -0.95 kg; 95%CI -1.20 to -0.69; 29 RCTs; n=5,680; moderate certainty) or lifestyle counselling (MD -1.25 kg; 95%CI -1.64 to -0.86; 36 RCTs; n=9,083; low certainty). The risk of weight gain exceeding guidelines was also reduced by dietary intervention (RR 0.65; 95%CI 0.54 to 0.77; 4 RCTs; n=538; very low certainty), exercise intervention (RR 0.77; 95%CI 0.69 to 0.87; 16 RCTs; n=4,333; low certainty) and lifestyle counselling intervention (RR 0.83; 95%CI 0.78 to 0.89; 29 RCTs; n=7,905; low certainty). The risk of postnatal weight retention was reduced with lifestyle counselling (MD -1.19 kg; 95%CI -1.62 to -0.76; 11 RCTs; n=2,483; moderate certainty). There was no clear difference in postnatal weight retention with a dietary intervention (MD -0.55 kg; 95%CI -2.02 to 0.92; 2 RCTs; n=556; very low certainty) or exercise intervention (MD –0.20 kg; 95%CI –1.48 to 1.09; 5 RCTs; n=388; moderate certainty). 

Risk of gestational diabetes was reduced by exercise interventions (RR 0.74; 95%CI 0.60 to 0.90; 20 RCTs; n=5,592; low certainty), probably reduced by lifestyle counselling (RR 0.90; 95%CI 0.81 to 1.01; 26 RCTs; n=9,011; moderate certainty) with no differences seen with dietary interventions (RR 0.86; 95%CI 0.64 to 1.17; 6 RCTs; n=1,424; very low certainty).  

There was a reduced risk of gestational hypertension with dietary intervention (RR 0.29; 95%CI 0.13 to 0.61; 3 RCTs; n=429; moderate certainty) or exercise intervention (RR 0.51; 95%CI 0.37 to 0.71; 7 RCTs; n=3,060; moderate certainty) but not with lifestyle counselling (RR 0.99; 95%CI 0.77 to 1.28; 13 RCTs; n=4,890; low certainty). No difference in risk of pre-eclampsia was seen with any type of intervention (low to moderate certainty). 

Risk of caesarean section was reduced with exercise intervention (RR 0.85; 95%CI 0.74 to 0.98; 25 RCTs; n=5,704; moderate certainty) and probably reduced with lifestyle counselling (RR 0.95; 95%CI 0.89 to 1.02; 25 RCTs; n=9,049; low certainty). There was no difference in risk of caesarean section with a dietary intervention (RR 0.85; 95%CI 0.64 to 1.11; 6 RCTs; n=1,461; very low certainty). 

The risk of antenatal depression was reduced with exercise intervention (RR 0.44; 95%CI 0.32 to 0.61; 6 RCTs; n=798; moderate certainty) but not lifestyle counselling (RR 0.99; 95%CI 0.80 to 1.22; 2 RCTs; n=2,908; low certainty). The risk of postnatal depression was reduced with exercise intervention (RR 0.47; 95%CI 0.34 to 0.65; 5 RCTs; n=1,613; moderate certainty). 

The risk of preterm birth was reduced with a dietary intervention (RR 0.43; 95%CI 0.24 to 0.79; 4 RCTs; n=1,296; moderate certainty), probably reduced with lifestyle counselling (RR 0.85; 95%CI 0.72 to 1.01; 18 RCTs; n=7,497; moderate certainty) but not changed by exercise intervention (RR 0.95; 95%CI 0.74 to 1.22; 15 RCTs; n=4,388; moderate certainty).  

No difference was seen in risk of macrosomia >4,000g with dietary intervention (RR 0.97; 95%CI 0.84 to 1.11; 3 RCTs; n=1,138; very low certainty) but there was a reduction with exercise intervention (RR 0.75; 95%CI 0.59 to 0.96; 15 RCTs; n=4,759; moderate certainty) and a probable reduction with lifestyle counselling (RR 0.91; 95%CI 0.82 to 1.01; 17 RCTs; n=7,664; low certainty). There was also a reduction of risk of macrosomia >4,500 g with lifestyle counselling (RR 0.67; 95%CI 0.46 to 0.97; 5 RCTs; n=3,435; moderate certainty). There was no difference seen in risk of low birthweight with an exercise intervention (RR 0.94; 95%CI 0.68 to 1.28; 11 RCTs; n=3,247; moderate certainty) or lifestyle counselling (RR 0.87; 95%CI 0.65 to 1.17; 4 RCTs; n=3,665; low certainty). There was a possible reduction in risk of large-for-gestational age with lifestyle counselling (RR 0.89; 95%CI 0.79 to 1.00; 22 RCTs; n=8,455; moderate certainty) but no clear difference in risk with the other interventions. 

There was no clear difference in risk of small-for-gestational age, Apgar score <7 at 5 minutes or weight in early childhood with any intervention. 

An Australian study found that antenatal lifestyle interventions for preventing gestational diabetes and hypertensive diseases of pregnancy are likely to be cost effective (Bailey et al 2020). Studies from overseas found that lifestyle interventions were cost-effective for gestational weight gain (Broekhuizen et al 2018) but not blood glucose levels, insulin resistance (Oostdam et al 2012); (Broekhuizen et al 2018) or infant weight (Oostdam et al 2012), were inconsistent regarding quality-adjusted life years (Oostdam et al 2012); (Broekhuizen et al 2018) and a better understanding of the short- and long-term costs of large for gestational age and weight gain exceeding IOM recommendations is necessary O'Sullivan et al 2020. 

11.5 Practice summary: nutrition and physical activity

Nutrition

When: All antenatal visits

Who: Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander Health Practitioner; Aboriginal and Torres Strait Islander Health Worker; multicultural health worker; accredited dietitian; nutritionist

• Assess levels of nutrition:
  Ask women about their current eating patterns.
• Promote healthy eating:
  Explain the benefits of healthy nutrition for the mother and baby. Give examples of healthy dietary patterns, including ‘eating a rainbow’ (ie eating fruits and vegetables of different colours to promote adequate vitamin and mineral consumption).
• Discuss foods to avoid:
  Give examples of foods that can cause harm during pregnancy, including alcohol, sources of listeria and fish high in mercury (see Table C2).
• Discuss use of nutritional supplements:
  Explain that some supplements (folic acid, iodine) are recommended for all women during some stages of pregnancy, while others may be harmful at levels higher than the recommended daily intake.
• Consider referral:
  Referral to an accredited practising dietitian may be a consideration if there is concern about the quality of nutritional intake, the woman would like information about nutrition for herself and her family, clinical assessment confirms that the women is underweight, overweight or obese or there are other factors of concern (eg diabetes, gastrointestinal disorders). An accredited practicing dietitian may also need to be consulted if the woman is under 18 years of age due to increased dietary need; most guidelines are based on adult needs.
• Take a holistic approach:
  Tailor dietary advice to the individual woman. Consider the availability and affordability of foods appropriate to the woman’s cultural practices and preferences and the need for and affordability of supplements.

Physical activity

When: All antenatal visits.

Who: Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander Health Practitioner; Aboriginal and Torres Strait Islander Health Worker; multicultural health worker; physiotherapist, accredited exercise physiologist or accredited exercise scientist

• Assess levels of activity:
  Ask women about their current levels of physical activity, including the frequency, intensity, duration and type of activity.
• Promote healthy levels of physical activity
  Give women advice based on the Australian Physical Activity and Sedentary Behaviour Guidelines and explain that physical activity during pregnancy has health benefits and is safe.
• Provide information
  Give information about local supports for physical activity (eg women’s walking groups, swimming clubs). Advise women to avoid exercising in the heat of the day and to drink plenty of water when active.
• Consider referral:
  Referral to an accredited exercise physiologist may be a consideration if there is a concern about the safety of physical activity for the woman and her family or the woman has not been physically active prior to pregnancy, clinical assessment confirms underweight or overweight of the woman or there are other factors of concern (e.g. diabetes, musculoskeletal conditions).
• Take a holistic approach
  Assist women to identify ways of being physically active that are appropriate to their cultural beliefs and practices (eg activities they can do at home)

11.6 Resources

11.6.1 Nutrition

• FSANZ (2011) Mercury in Fish. Food Standards Australia New Zealand. Accessed: 13 August 2018.
• FSANZ (2011) Listeria. Food Standards Australia New Zealand. Accessed: 13 August 2018.
• NHMRC (2013) Australian Dietary Guidelines. Canberra: National Health and Medical Research Council.
• NHMRC (2010) NHMRC Public Statement: Iodine Supplementation for Pregnant and Breastfeeding Women. Canberra: National Health and Medical Research Council.
• NHMRC (2006) Nutrient Reference Values for Australia and New Zealand. Canberra: National Health and Medical Research Council.

11.6.2 Physical activity

• Brown et al (2020) Evidence-based Physical Activity Guidelines for Pregnant Women. Report prepared for the Australian Government Department of Health.  
• DoH (2014) Australia’s Physical Activity and Sedentary Behaviour Guidelines. 
• RANZCOG (2020) RANZCOG_SITE/media/RANZCOG-MEDIA/Women%27s%20Health/Statement%20and%20guidelines/Clinical-Obstetrics/Exercise-during-pregnancy-(C-Obs-62).pdf?ext=.pdf">Exercise During Pregnancy