Anaemia

Antenatal care provides an opportunity to identify women with possible anaemia. If anaemia is diagnosed, supplementation with the deficient nutrient (most commonly iron) may be advised where indicated.

30.1 Background

Anaemia is a lower than normal concentration of haemoglobin or number of red blood cells, which results in reduced capacity of the blood to carry oxygen. During pregnancy, the WHO criteria for mean minimum normal haemoglobin concentration in healthy pregnant women is 110 mg/dL in the first half of pregnancy and 105 mg/ dL in the second. Iron deficiency is the most common cause of anaemia in pregnancy worldwide WHO 2001, but other deficiencies may also cause anaemia:

• iron deficiency: demand for iron is increased during pregnancy NPS 2010 and insufficient iron intake or absorption (eg diet poor in iron-rich foods and/or rich in foods that diminish iron absorption) or blood loss (eg due to gastrointestinal parasites) ACOG 2008 can result in microcytic anaemia
• folate deficiency: demand for folate is also increased during pregnancy and inadequate dietary intake, prolonged vomiting or impaired absorption (eg due to gastric bypass surgery or gastrointestinal conditions) can result in macrocytic anaemia
• vitamin B12 deficiency: prolonged inadequate intake (eg limited access to source foods or vegetarian diet) or impaired absorption (eg due to gastric bypass surgery, pernicious anaemia or gastrointestinal conditions) can result in macrocytic anaemia
• haemoglobinopathies: these include sickle cell anaemia and thalassaemia (see Chapter 31).

Symptoms of anaemia include general weakness and tiredness but the threshold concentrations of haemoglobin at which these symptoms occur in pregnancy is not known (Reveiz et al 2011).

30.1.1 Prevalence of iron, folate and vitamin B12 deficiency during pregnancy

Estimates suggest that one-quarter of the world’s population has anaemia. The burden of anaemia is considerably higher among indigenous populations compared to the general population (Khambalia et al 2011).

The prevalence of iron-deficiency anaemia during pregnancy is generally low (< 20%) in developed countries (van den Broek 2003) and higher (35–75%) in developing countries (Africa, Asia, South America) van den Broek 2003, Kalaivani 2009 and areas of socioeconomic disadvantage USPSTF 2006. Reported predictors for having anaemia by 32 weeks gestation include young maternal age, non-white ethnic origin and increasing parity (Barroso et al 2011).

Few studies have reported the prevalence of iron-deficiency anaemia during pregnancy in Australia. Iron-deficiency anaemia was identified in 18% of pregnant women in a Tasmanian study (n=2,654) (Khalafallah et al 2010) and in 11% of pregnant women in a South Australian study (n=430) (Zhou et al 2006).

Data from Queensland suggest higher prevalence of iron-deficiency anaemia during pregnancy among Aboriginal than non-Indigenous women (Wills & Coory 2008). Smaller studies have found a prevalence of anaemia during pregnancy among Aboriginal women of 50% in remote Northern Territory communities (Bar-Zeev et al 2013), 12% across 34 Aboriginal community health services (range 3–22%) (n=535) (Rumbold et al 2011) and 10% in Brisbane (n=1,523) (Stapleton et al 2011).

Data from Western Australia and South Australia show higher prevalence of iron-deficiency anaemia during pregnancy among adolescent (14%) than adult women (6%) and among Aboriginal (23–25%) compared with non-Indigenous (8–10%) adolescent women Westernberg et al 2002, Lewis et al 2009.

Mandatory fortification of flour with folic acid has reduced the prevalence of low folate levels among Australian women of childbearing age (0.16% in 2010) (Brown et al 2011). A Western Australian study found low folate levels in 10% of Aboriginal women before flour fortification (Maxwell et al 2012).

Vitamin B12 deficiency is common in most of the developing world Stabler & Allen 2004, Allen 2009. Few studies have examined the prevalence of vitamin B12 deficiency in Australia (Flood et al 2006). However, there is emerging evidence of vitamin B12 deficiency among refugees due to limited or no sources of animal foods before resettlement Benson et al 2010, Benson et al 2013.

Preventing iron deficiency (through inclusion of iron-rich foods in the diet and/or iron supplementation) is discussed in Section 11.3.2.

30.1.2 Risks associated with iron, folate and vitamin B12 deficiency during pregnancy

Severe iron-deficiency anaemia (haemoglobin concentration <70 mg/dL) can cause cardiac failure, Lops 1995, WHO 1992, Williams & Wheby 1992 and reduce tolerance of blood loss associated with birth. It is unclear whether mild to moderate anaemia is associated with poor outcomes (Reveiz et al 2011).

Deficiencies of folate De-Regil et al 2010 or vitamin B12 (Molloy et al 2009) during pregnancy are associated with neural tube defects.

30.2 Testing for anaemia

Routinely offering a full blood count early in pregnancy and at 28 weeks is recommended in the United Kingdom NICE 2008 and in Australia RANZCOG 2009. Initial haemoglobin concentration is usually assessed in the context of this full blood count.

30.2.1 Assessing haemoglobin concentration

During pregnancy, maternal red cell mass and plasma volume increase and the haemoglobin concentration is reduced NICE 2008. Haemoglobin is therefore checked against gestation-related thresholds.

 

30.2.2 Further investigations

Haemoglobin concentration is not sensitive enough to be the sole means of diagnosing anaemia. Diagnostic tests include:

• full blood count (if this has not already been conducted)
• serum ferritin, which is the most sensitive single test to detect adequate iron stores (90% sensitivity at a cut-off of 30 mg/litre) (Breymann 2002)
• specific tests for folate and vitamin B12, if mean cell volume is high.

30.3 Treating iron-deficiency anaemia

30.3.1 Effectiveness and safety of treatments for iron-deficiency anaemia

The evidence on treatments for iron-deficiency anaemia covers a very wide range of supplements, doses and routes of administration and focuses on changes in maternal haemoglobin concentration.

• Iron supplementation improves maternal haemoglobin concentrations, but there is a lack of evidence about the overall benefits of treating mild iron-deficiency anaemia in pregnancy (Reveiz et al 2011).
• Oral iron can cause gastrointestinal adverse effects (eg nausea, constipation) (Reveiz et al 2011). Intramuscular or intravenous iron is more effective than oral iron, but may have adverse effects (venous thrombosis and allergic reactions for intravenous treatment and pain, discolouration and allergic reactions for intramuscular treatment) (Reveiz et al 2011).

Iron as part of general nutritional supplementation is discussed in Section 11.3.2. Given the lack of evidence on outcomes, the recommendation is not to routinely offer iron supplementation to women during pregnancy.

30.3.2 Dose of supplementation 

Recent studies provide high-level evidence on lower doses of iron supplementation. Iron supplements that are low dose (eg 20 mg) or taken less often than daily appear to be effective in treating anaemia in pregnancy with fewer gastrointestinal side effects compared with high-dose (eg 80 mg) or daily supplements de Souza et al 2004, Sharma et al 2004, Zhou et al 2009, Reveiz et al 2011.

30.3.3 Other considerations

Treatment for hookworm infestation should also be considered in areas of high prevalence.

30.4 Discussing anaemia

When haemoglobin concentration is low, points for discussion include:

• while anaemia in pregnancy is most commonly associated with iron deficiency, deficiencies of folate or vitamin B12 also result in anaemia and further tests are required to identify the cause
• if a deficiency is identified, supplementation with the appropriate nutrient can correct the deficiency
• supplements can be combined with foods rich in the relevant nutrient:
  • iron-rich foods include meat, seafood and poultry; including a vitamin C rich fruit or vegetable in each meal and limiting tea and coffee to between meals aids absorption (Marsh et al 2009)
  • foods rich in folate include fortified bread and cereals, dried beans and peas, dark green vegetables and citrus fruit and juice
  • foods that contain vitamin B12 include meat, eggs, milk and cheese.

30.5 Practice summary: anaemia

When

Early in pregnancy and at 28 weeks gestation.

Who

• Midwife
• GP
• obstetrician
• Aboriginal and Torres Strait Islander Health Practitioner
• Aboriginal and Torres Strait Islander Health Worker
• multicultural health worker.

What

• Discuss the reasons for testing for anaemia
  Explain that anaemia causes tiredness and can have other effects on the pregnancy.
• Explain the causes of anaemia
  Iron-deficiency anaemia is common during pregnancy. Other causes of anaemia may be a consideration for women who live in or have come from areas where folate or vitamin B12 deficiencies are common.
• Take a holistic approach
  Consider the availability of iron-rich foods appropriate to the woman’s cultural practices and preferences and the affordability of supplements. For women taking supplements for iron-deficiency, explore culturally appropriate, low cost ways for women to increase their fibre and fluid intake if they are experiencing constipation.
• Consider referral
  If there is concern about the quality of dietary iron intake or if the woman would like information about nutrition for herself and her family, consider referral to an accredited dietitian.
• Document and follow-up
  When a woman is tested for anaemia, tell her the results and note them in her antenatal record. Have a system in place so that women with iron-deficiency anaemia during pregnancy are given information about iron supplementation and receive ongoing follow-up, including further investigation if anaemia does not resolve after pregnancy.

30.6 Resources

• Remote Primary Health Care Manuals. (2017). Anaemia (weak blood) in pregnancy. In: Women’s Business Manual (6th edition). Alice Springs, NT: Centre for Remote Health.