There is limited evidence to support screening of all women for vitamin D deficiency in pregnancy and it is not possible to reliably identify women who are vitamin D deficient. However, some women and their babies may benefit from supplementation.
8.9.1 BackgroundVitamin D is essential for bone development in children and skeletal health in adults. It regulates calcium and phosphate absorption and metabolism. Vitamin D is obtained through the direct action of sunlight on the skin (90%) or through dietary nutrients (10%), in particular dairy products, eggs and fish. In the skin, provitamin D3 is activated by ultraviolet B light to form cholecalciferol (vitamin D3), which is converted in the liver to 25-hydroxyvitamin D (25-OHD). Vitamin D deficiency is defined as serum 25O-HD of ≤ 25 nmol/L and insufficiency as 26–50 nmol/L (ANZBMS 2005; Munns et al 2006).
Vitamin D deficiency in AustraliaEstimates of the prevalence of vitamin D deficiency in Australia vary but may be higher than previously thought (Nowson & Margerison 2002). Observational studies have reported vitamin D deficiency in a range of populations, with the following findings:
- 7.2% of women aged 20–90 in Geelong had serum 25O-HD lower than 28 nmol/L (n=861) (Pasco et al 2001);
- among women attending for antenatal care in Sydney (n=971)(Bowyer et al 2009), (n=308) (Clifton Bligh et al 2008) and rural Victoria (n=330) (Teale & Cunningham 2010), 15%, 11% and 5.2%, respectively had serum 25O-HD lower than 25 nmol/L, however studies did not report on women’s exposure to sunlight or covering of skin; and
- among high-risk groups, 80% of women with dark skin or covered skin (veiled) attending for antenatal care in Melbourne (n=82) had serum 25O-HD lower than 22.5 nmol/L (Grover & Morley 2001) and 81% of mothers of infants with rickets (n=55) had serum 25O-HD lower than 25 nmol/L (Nozza & Rodda 2001).
Risks associated with vitamin D deficiency in pregnancyMaternal vitamin D deficiency in pregnancy is associated with (Bowyer et al 2009):
- low serum calcium in the newborn, with or without convulsions (Watney et al 1971; Roberts et al 1973; Rosen et al 1974; Robinson et al 2006);
- rickets (Ford et al 1973; Moncrieff & Fadahunsi 1974; Nozza & Rodda 2001; Robinson et al 2006); and
- defective tooth enamel (Purvis et al 1973; Stimmler et al 1973).
- lower birth weights and a higher risk of being small for gestational age (Leffelaar et al 2010);
- lower newborn bone mineral accrual to be lower in the vitamin D deficient groups, although bone mineral density differences were not statistically significant (Viljakainen et al 2010); and
- greater femoral metaphyseal cross-sectional area and a higher femoral splaying index at 19 and 34 weeks pregnancy, suggesting that maternal vitamin D deficiency can influence fetal femoral development as early as 19 weeks pregnancy (Mahon et al 2010).
8.9.2 Vitamin D deficiency in pregnancy
Summary of the evidenceScreening for vitamin D deficiency is not considered a cost-effective option (NZ MOH 2008) and is recommended against in the United States (ACOG 2011). However, many health organisations recommend vitamin D supplementation during pregnancy (IOM 1997; CPS 2007; NZ MOH 2008; RCOG 2009; UK Dept Health 2009; Weggemans et al 2009).
Further research is needed concerning screening for vitamin D deficiency, including identifying predictive factors for vitamin D insufficiency and deficiency in Australia and determining the cost-effectiveness of routine screening of all women in pregnancy. Research is also needed into the effectiveness and safety of vitamin D supplementation.
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Groups at higher risk of vitamin D deficiencyTraditionally, women thought to be at high risk of vitamin D deficiency are dark-skinned inhabitants of high latitude or low sunshine climates (Holvik et al 2005; van der Meer et al 2006). Small studies of pregnant Asian women in England and Norway and black women from the United States have shown vitamin D insufficiency rates of more than 50% (Brooke et al 1980; Alfaham et al 1995; Brunvand et al 1996; Bodnar et al 2007a; Lee et al 2007). A study from the United Kingdom found 18% of white women were vitamin D deficient (<27 nmol/l) late in pregnancy (Gale et al 2008). Studies in the Netherlands (Djikstra et al 2007) and Lebanon (Nabulsi et al 2008) found that women who covered their skin during pregnancy were more likely to have babies deficient in vitamin D. High pre-pregnancy body mass index (BMI) has also been associated with low levels of vitamin D (Bodnar et al 2007b). Seasonal influences have been noted (Basile et al 2007; O’Riordan et al 2008).
A recent population-based study in south-eastern Sydney (Bowyer et al 2009) identified the following factors as being associated with vitamin D deficiency in mothers:
- maternal birthplace outside Australia (OR 2.2; 95% CI 1.4–3.5; p=0.001);
- dark skin (phototype V or VI)1 (OR 2.7; 95% CI 1.6–4.5; p<0.001);
- wearing a veil (OR 21.7; 95% CI 11.7–40.3; p<0.001); and
- younger maternal age (mean age 27.8 versus 29.9 for insufficiency and 30.3 for sufficiency) (OR 0.93; 95% CI 0.89–0.97; p<0.001).
Effectiveness of vitamin D supplementationVitamin D supplementation improves maternal vitamin D status during pregnancy (Yu et al 2009), which in turn directly influences the fetal and newborn supply of vitamin D (Brooke et al 1980). The NICE guidelines found no evidence that routine vitamin D supplementation for healthy women improves pregnancy outcomes but found that supplementation may be beneficial in groups of women at risk of deficiency:
- antenatal vitamin D supplementation improved the vitamin D status of African, African-Caribbean, far and middle Eastern, South Asian and Caucasian women, with no adverse effects reported (Brooke et al 1980; Cockburn et al 1980; Brooke et al 1981; Maxwell et al 1981; Greer et al 1981; 1982; Delvin et al 1986; Mallet et al 1986; Datta et al 2002);
- infants of South Asian mothers who received an antenatal vitamin D supplement achieved a higher body weight during the first year after birth than infants of mothers who received no antenatal vitamin D supplement (Brooke et al 1980; 1981; Maxwell et al 1981); and
- the effect of vitamin D supplements on infant bone mineral content was uncertain, with two studies having conflicting results (Congdon et al 1983; Greer & Marshall 1989).
- no reduction in risk of gestational hypertension or pre-eclampsia in a population-based study (Oken et al 2007);
- no significant effect of combined vitamin D and calcium supplementation on preventing preeclampsia in a small controlled trial (Chung et al 2009);
- no difference in birth weight in controlled trials (Brook et al 1980; Mallet et al 1986); and
- insufficient evidence of an association between 25-OHD levels and change in bone density in pregnancy (Cranney et al 2007).
Consensus-based recommendationviii. Offer vitamin D screening to women with limited exposure to sunlight (eg because they are predominantly indoors or usually protected from the sun when outdoors), or who have dark skin or a pre-pregnancy BMI of >30, as they may be at increased risk of vitamin D deficiency and benefit from supplementation for their longterm health. Base decisions about whether to offer screening on these factors, season and climate.
8.9.3 Practice summary — testing for vitamin D deficiencyWhen — In the antenatal period
Who — Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander health worker; multicultural health worker
- Document and follow-up — If a woman is tested for vitamin D deficiency, note the results in her record. Have a system in place so that women who are found to be deficient in vitamin D are given ongoing follow-up and information about supplementation.
8.9.4 ResourcesAustralian And New Zealand Bone And Mineral Society, Osteoporosis Australia, The Australasian College Of Dermatologists, The Cancer Council Australia (2007) Risks and Benefits of Sun Exposure Position Statement. For more information please visit - www.cancer.org.au//File/PolicyPublications/PSRisksBenefitsSunExposure03May07.pdf (This website link was valid at the time of submission).
Cancer Council Australia (2008) How Much Sun Is Enough? Getting the Balance Right. Vitamin D and Sun Protection. For more information please visit - www.cancer.org.au/File/Cancersmartlifestyle/Howmuchsunisenough.pdf (This website link was valid at the time of submission).
NHMRC (2005) Nutrient Reference Values for Australia and New Zealand. Canberra: National Health and Medical Research Council. For more information please visit National Health and Medical Research Council website.
8.9.5 ReferencesACOG (2011) Committee opinion no. 495: vitamin D: screening and supplementation during pregnancy. Obstet Gynecol 118(1): 197–98.
Alfaham M, Woodhead S, Pask G et al (1995) Vitamin D deficiency: a concern in pregnant Asian women. Brit J Nutrition 73: 881–87.
ANZBMS (2005) Vitamin D and adult bone health in Australia and New Zealand: a position statement. Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia & Osteoporosis Australia. Med J Aust 182, 281–85.
Basile LA, Taylor SN, Wagner CL et al (2007) Neonatal vitamin D status at birth at latitude 32 degrees 72’: evidence of deficiency. J Perinatol 27(9): 568–71.
Bodnar LM, Simhan HN, Powers RW et al (2007a) High prevalence of vitamin D insufficiency in black and white pregnant women residing in the Northern United States and their neonates. J Nutrition 137: 447–52.
Bodnar LM, Catov JM, Roberts JM et al (2007b) Prepregnancy obesity predicts poor vitamin D status in mothers and their neonates. J Nutrition 137(11): 2437–42.
Bowyer L, Catling-Paull C, Diamond T et al (2009) Vitamin D, PTH and calcium levels in pregnant women and their neonates. Clin Endocrinol 70(3): 372–77.
Brooke OG, Brown IR, Bone CD et al (1980) Vitamin D supplements in pregnant Asian women: effects on calcium status and fetal growth. Brit Med J 280: 751–54.
Brooke OG, Butters F, Wood C (1981) Intrauterine vitamin D nutrition and postnatal growth in Asian infants. Brit Med J 283: 1024.
Brunvand L, Quigstad E, Urdal P et al (1996) Vitamin D deficiency and fetal growth. Early Hum Dev 45: 27–33.
Chung M, Balk EM, Brendel M et al (2009) Vitamin D and calcium: a systematic review of health outcomes. Evid Rep Technol Assess 183: 1-420.
Clifton Bligh RJ, McElduff P, McElduff A (2008) Maternal vitamin D deficiency, ethnicity and gestational diabetes.Diabetic Med 25(6): 678–84.
Cockburn F, Belton NR, Purvis RJ (1980) Maternal vitamin D intake and mineral metabolism in mothers and their newborn infants. Brit Med J 281(6232): 11–14.
Congdon P, Horsman A, Kirby PA (1983) Mineral content of the forearms of babies born to Asian and white mothers. Brit Med J 286(6373): 1233–35.
CPS (2007) Vitamin D Supplementation: Recommendations for Canadian Mothers and Infants. Canadian Paediatric Society, First Nations, Inuit and Métis Health Committee. Paediatr Child Health12 (7): 583–98.
Cranney A, Horsley T, O’Donnell S et al (2007) Effectiveness and safety of vitamin D in relation to bone health. Evid Rep Technol Assess 158: 1–235.
Datta S, Alfaham M, Davies DP et al (2002) Vitamin D deficiency in pregnant women from a non-European ethnic minority population – an interventional study. BJOG 109(8): 905–08.
Delvin EE, Salle BL, Glorieux FH et al (1986) Vitamin D supplementation during pregnancy: effect on neonatal calcium homeostasis. J Pediatr 109(2): 328–34.
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Devereux G, Litonjua AA, Turner SW et al (2007) Maternal vitamin D intake during pregnancy and early childhood wheezing. Am J Clin Nutrition 85(3): 853–59.
Ford JA, Davidson DC, McIntosh WB et al (1973) Neonatal rickets in Asian immigrant population. Brit Med J 3: 211–12.
Gale CR, Robinson SM, Harvey NC et al (2008) Maternal vitamin D status during pregnancy and child outcomes. Eur J Clin Nutrition 62(1): 68–77.
Greer FR & Marshall S (1989) Bone mineral content, serum vitamin D metabolite concentrations, and ultraviolet B light exposure in infants fed human milk with and without vitamin D2 supplements. J Pediatrics 114(2): 204–12.
Greer FR, Searcy JE, Levin RS (1981) Bone mineral content and serum 25-hydroxyvitamin D concentration in breast-fed infants with and without supplemental vitamin D. J Pediatrics 98(5): 696–701.
Greer FR, Searcy JE, Levin RS et al (1982) Bone mineral content and serum 25-hydroxyvitamin D concentrations in breast-fed infants with and without supplemental vitamin D: one-year follow-up. J Pediatrics 100(6): 919–22.
Grover S & Morley R (2001) Vitamin D deficiency in veiled or dark-skinned pregnant women. Med J Aust 175: 251–52.
Holvik K, Meyer HE, Haug E et al (2005) Prevalence and predictors of vitamin D deficiency in five immigrant groups living in Oslo, Norway: the Oslo immigrant health study. Eur J Clin Nutr 59: 57–63.
IOM (1997) Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Institute of Medicine. Washington DC: National Academy Press, 1997.
Lee JM, Smith JR, Philipp BL et al (2007) Vitamin D deficiency in a healthy group of mothers and newborn infants. Clin Pediatr 46(1): 42–44.
Leffelaar ER, Vrijkotte TG, van Eijsden (2010) Maternal early pregnancy vitamin D status in relation to fetal and neonatal growth: results of the multi-ethnic Amsterdam Born Children and their Development cohort. Brit J Nutr 104(1): 108-117.
Litonjua AA (2009) Childhood asthma may be a consequence of vitamin D deficiency. Curr Op Allergy Clin Immunol 9(3): 202–07.
Mahon P, Harvey N, Crosier S et al (2010) Low maternal vitamin D status and fetal bone development: Cohort study. J Bone Mineral Res 25(1): 14–19.
Mallet E, Gugi B, Brunelle P et al (1986) Vitamin D supplementation in pregnancy: a controlled trial of two methods. Obstet Gynecol 68(3): 300–04.
Marya RK, Rathee S, Lata V et al (1981) Effects of vitamin D supplementation in pregnancy. Gynecol Obstet Investigation 12: 155–161.
Maxwell JD, Ang L, Brooke OG et al (1981) Vitamin D supplements enhance weight gain and nutritional status in pregnant Asians. Brit J Obstet Gynaecol 88: 987–91.
McGrath J (2001) Does ’imprinting’ with low prenatal vitamin D contribute to the risk of various adult disorders? Med Hypotheses 56(3): 367–71.
Moncrieff M & Fadahunsi TO (1974) Congenital rickets due to maternal vitamin D deficiency. Arch Dis Child 49: 810–11.
Morley R, Carlin JB, Pasco JA et al (2006) Maternal 25-hydroxyvitamin D and parathyroid hormone concentrations and offspring birth size. J Clin Endocrinol Metabolism 91: 906–12.
Munns C, Zacharin MR, Rodda CP et al (2006) Prevention and treatment of infant and childhood vitamin D deficiency in Australia and New Zealand: a consensus statement. Med J Aust 185: 268–72.
Nabulsi M, Mahfoud Z, Maalouf J et al (2008) Impact of maternal veiling during pregnancy and socioeconomic status on offspring’s musculoskeletal health. Osteoporosis Int 19(3): 295–302.
Nowson C & Margerison C (2002) Vitamin D intake and vitamin D status of Australians. Med J Aust 177: 149–52.
Nozza JM & Rodda CP (2001) Vitamin D deficiency in mothers of infants with rickets. Med J Aust 175: 253–55.
NZ MOH (2008) NSAC ‘Statement of Advice’: Should Women be Screened for Vitamin D During Pregnancy in New Zealand ? Ministry of Health, New Zealand.
O’Riordan MN, Kiely M, Higgins JR et al (2008) Prevalence of suboptimal vitamin D status during pregnancy. Irish Med J 101(8): 240, 242–43.
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Oken E, Ning Y, Rifas-Shiman SL et al (2007) Diet During Pregnancy and Risk of Preeclampsia or Gestational Hypertension. Annals Epidemiol 17(9): 663–68.
Pasco J, Henry M, Nicholson G et al (2001) Vitamin D status of women in the Geelong Osteoporosis Study: association with diet and casual exposure to sunlight. Med J Aust 175: 401–05.
Purvis RJ, Barrie WJ, MacKay GS et al (1973) Enamel hypoplasia of the teeth associated with neonatal tetany: a manifestation of maternal vitamin-D deficiency. Lancet 2: 811–14.
RCOG (2009) Scientific Advisory Committee Opinion Paper 16. For more information please visit Royal College of Obstetricians and Gynaecologists website.
Roberts RA, Cohen MD Forfar JO (1973) Antenatal factors associated with neonatal hypocalcaemic convulsions. Lancet 2: 809–11.
Robinson PD, Hogler W, Craig ME et al (2006) The re-emerging burden of rickets: a decade of experience from Sydney. Arch Dis Child 91: 564–68.
Rosen JF, Roginsky M, Nathenson G et al (1974) 25-Hydroxyvitamin D. Plasma levels in mothers and their premature infants with neonatal hypocalcemia. Am J Dis Child 127: 220–23.
Stimmler L, Snodgrass GJ, Jaffe E (1973) Dental defects associated with neonatal symptomatic hypocalcaemia. Arch Dis Child 48: 217–20.
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Van der Meer MI, Karamali NS, Boeke AJ et al (2006) High prevalence of vitamin D deficiency in pregnant non-Western women in The Hague, Netherlands. Am J Clin Nutr 84: 350–53.
van der Mei IA, Ponsonby AL, Engelsen O et al (2007) The high prevalence of vitamin D insufficiency across Australian populations is only partly explained by season and latitude. Environ Health Perspect 115(8): 1132–39.
Vanlint SJ, Morris HA, Newbury JW et al (2011) Vitamin D insufficiency in Aboriginal Australians. Med J Aust 194 (3): 131–34.
Viljakainen HT, Saarnio E, Hytinantti T et al (2010) Maternal vitamin D status determines bone variables in the newborn. J Clin Endocrinol Metabolism 95(4): 1749–57.
Watney PJ, Chance GW, Scott P et al (1971) Maternal factors in neonatal hypocalcaemia: a study in three ethnic groups. Brit Med J 2: 432–36.
Weggemans RM, Schaafsma G, Kromhout D (2009) Towards an adequate intake of vitamin D. An advisory report of the Health Council of the Netherlands. Eur J Clin Nutr 63(12): 1455–57.
Yu CK, Sykes L, Sethi M et al (2009) Vitamin D deficiency and supplementation during pregnancy. Clin Endocrinol 70(5): 685–90.
1 Defined using the Fitzpatrick phototypes in response to the question ‘If your skin was untanned, for example, after winter and you exposed it to the sun for 30–45 min what would happen?’ — V Brown: rarely burns, tans profusely (dark brown); VI Dark brown or black: never burns, deeply tans (black).