There is limited evidence to support testing of all women for vitamin D status in pregnancy and the benefits and harms of vitamin D supplementation in pregnancy remain unclear.
Vitamin 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.
Definitions of vitamin D sufficiency vary, with Australian organisations generally considering levels lower than 50 nmol/L as suboptimal .
47.1.1 Vitamin D status in Australia
The Australian Health Survey 2011–12 nmol/L was:found that most Australian adults had Vitamin D levels above 50 nmol/L, with 23% having lower levels. Prevalence of vitamin D levels lower than 50
- lower in summer (14%) and higher in winter (36%)
- relatively low across all the States and Territories in summer, ranging from 6% in Queensland to 19% in New South Wales
- particularly high in winter for those living in the south-eastern states of Australia, such as Victoria and the Australian Capital Territory (49% compared with only 16% and 13% respectively in summer) but remained relatively low in winter for those in Queensland and the Northern Territory.
Differences were seen across geographical areas, with vitamin D levels lower than 50 nmol/L more common in major cities (27%) than in inner regional (16%), outer regional (13%) and remote areas (9%). Vitamin D levels lower than 50 nmol/L were much more common among people born in Southern and Central Asia, North-East Asia, South-East Asia, North Africa and the Middle East.
The Australian Aboriginal and Torres Strait Islander Health Survey nmol/L. This pattern was similar for both men and women. Vitamin D levels lower than 50 nmol/L were more common in remote areas (38.7%) than in non-remote areas (23.0%) and vitamin D levels varied considerably by season.found that, in 2012–13, 26.5% Aboriginal and Torres Strait Islander adults had a vitamin D level lower than <50
Observational studies in Australia have reported vitamin D status in a range of populations:
- at two antenatal clinics in the Australian Capital Territory and New South Wales, the prevalence of levels lower than 50 nmol/L was 35% in Canberra and 25.7% in Campbelltown
- in a largely low-risk antenatal population in rural Victoria, around 5% had levels lower than 25 nmol/L and, at a Victorian metropolitan maternity service, 55% of women had vitamin D levels lower than 50 nmol/L
- among women booking for antenatal care in Cairns, there were no significant differences overall in women’s vitamin D levels based on Indigenous status and all women had levels higher than 50 nmol/L
- among women attending for antenatal care in Kalgoorlie, 56% of Aboriginal women and 20% of non- Aboriginal women had vitamin D levels lower than 50 nmol/L
- among Indigenous women receiving antenatal care in the Northern Territory, mean maternal vitamin D level was 104 nmol/L during pregnancy (mean 32 weeks gestation) and 80 nmol/L at birth and mean cord blood level was 54 nmol/L
- compared to migrant women without a refugee background, vitamin D levels lower than 75 nmol/L were generally more common among refugee women
- risk-based testing for vitamin D status in pregnancy (South Australian Perinatal Practice Guidelines, in which ‘high-risk’ groups are defined as veiled, dark-skinned and house-bound women) failed to detect over half of women with vitamin D levels lower than 60 nmol/L .
47.1.2 Vitamin D status and maternal and pregnancy outcomes
Recent studies have explored possible associations between vitamin D status in pregnancy and subsequent outcomes. This evidence is generally of low quality and heterogeneous (ie in definition of optimal level, timing of serum testing) and findings are inconsistent.
- Gestational diabetes and glucose tolerance: One cohort study nmol/L may be more likely to experience gestational diabetes (aOR 2.2; 95%CI 0.8 to 5.5), while another found no clear difference (aOR: 1.08; 95% CI: 0.74 to 1.56) . A cross-sectional study suggested that, compared to vitamin D levels higher than 74 nmol/L in early pregnancy, levels lower than 50 nmol/L (p=0.008) or 50–74 nmol/L (p=0.005) increased the risk of gestational diabetes . Another cross-sectional study found that increases in maternal vitamin D were associated with decreases in fasting glucose (p=0.012) . suggested that women with vitamin D levels lower than 25
- Pre-eclampsia: The evidence was largely consistent in finding no association between vitamin D level and the risk of pre-eclampsia in cohort studies and a case series .
- Preterm birth: No significant association between vitamin D level and preterm birth was found in a cohort study (p=0.09) and a case series (p=0.11) .
- Small for gestational age: The frequency of small-for-gestational-age newborns in cohort studies was similar in women with vitamin D levels below or above 20 nmol/L or was increased with levels below 29.9 nmol/l (aOR 1.9 95%CI 1.4 to 2.7) or below 25 nmol/L (aOR 1.58 95%CI 1.06 to 2.35, compared to 50–75 nmol/L) .
- Birth weight: A cohort study nmol/L and lower birth weights (–64.0 g, 95%CI –107.1 to –20.9). and a case series found no association between maternal first trimester vitamin D levels and neonatal birth weight. Another cohort study found an association between maternal vitamin D levels below 29.9
- Macrosomia and infant growth: A cohort study found that maternal vitamin D levels lower than 50 nmol/L were associated with increased risk of fetal macrosomia (abdominal circumference 90th centile; p=0.041) but not with rapid growth (p=0.11). Other cohort studies found an association between maternal vitamin D level below 29.9 nmol/L and accelerated growth or risk of overweight at age 1 year (p=0.03), but not at 4 years (p=0.721) .
47.2 Vitamin D status in pregnancy
Current guidance in Australia nmol/L. Guidance in Australia andNew Zealand also suggests consideration of a daily dose of 400 IU for pregnant women at higher risk (without testing) . In the United Kingdom, it is recommended that all women be advised early in pregnancy to take a supplement of 400 IU daily ., New Zealand and the United States suggests that testing be considered for women at high risk of suboptimal vitamin D levels and supplementation advised for pregnant women with levels lower than 50
47.2.1 Determinants of vitamin D status in pregnancy
The recent evidence on the determinants of vitamin D status in pregnancy is largely observational and of varying quality. While the definitions used varied across studies, the evidence was consistent that lower vitamin D levels in pregnancy are associated with:
- darker skin phototype
- increasing body mass index (BMI)
- season .
47.2.2 Benefits and harms of vitamin D supplementation
The clinical utility of testing vitamin D status is reliant on there being evidence for benefits from supplementation. While numerous studies have investigated vitamin D supplementation with and without calcium compared to placebo or no treatment, the evidence on the harms and benefits of vitamin D supplementation remains unclear.
- Serum vitamin D levels: Studies were consistent in finding that vitamin D supplementation increased vitamin D levels in women (low quality) and newborns . However, a Cochrane review noted that the clinical significance of increased maternal vitamin D concentrations remains unclear .
- Maternal outcomes: Evidence from the Cochrane review RR 0.52; 95%CI 0.25 to 1.05; low quality) and gestational diabetes (RR 0.43; 95%CI 0.05 to 3.45; very low quality) among women supplemented with vitamin D compared to those receiving placebo or no treatment, though neither result was statistically significant. Among women supplemented with vitamin D plus calcium, there was a reduced risk of pre-eclampsia (RR 0.51; 95%CI 0.32 to 0.80; moderate quality) and the data suggest a reduced risk of gestational diabetes (data from a single study) (RR 0.33; 95%CI 0.01 to 7.84; low quality). suggests a reduced risk of pre-eclampsia (
- Birth outcomes: The Cochrane review found a reduced risk of preterm birth compared to no treatment or placebo with vitamin D alone (RR 0.36; 95%CI 0.14 to 0.93; moderate quality) but an increased risk with vitamin D plus calcium (RR 1.57; 95%CI 1.02 to 2.43; moderate quality) , while a later RCT found no significant effect on gestational age at birth among women receiving vitamin D plus calcium (p=0.37) .
The Cochrane review of studies comparing vitamin D supplementation alone with no supplement found a reduced risk of low birth weight (RR 0.4; 95%CI 0.24 to 0.67; moderate quality), a possible increase in infant length (mean difference [MD] 0.70, 95%CI –0.02 to 1.43) and head circumference (MD 0.43, 95%CI 0.03 to 0.83) and no clear difference in rates of caesarean section (RR 0.95; 95%CI 0.69 to 1.31), stillbirths (RR 0.35; 95%CI 0.06 to 1.99) or neonatal deaths (RR 0.27; 95%CI 0.04 to 1.67) . Another systematic review found that the evidence to support a relationship between maternal vitamin D status and birth weight is limited by its observational nature . A later RCT found no clear differences in birth weight (p=0.88), length (p=0.94), head circumference (p=0.13) or mode of birth (p=0.26) among newborns of women receiving vitamin D plus calcium and those receiving no intervention .
- Infant outcomes: A systematic review found that the evidence to support an association between maternal vitamin D status and infant bone mass was limited by its observational nature and that evidence on serum calcium concentrations was limited by risk of bias. RCTs found that, compared to women receiving no supplement, there was no clear difference in bone mineral content in newborns of mothers receiving vitamin D alone (p=0.21) or with calcium (p=0.63) .
- Vitamin D dosage: Studies were consistent in finding that vitamin D level increased with dose (low quality evidence) IU daily found no difference in birth weight (p=0.8) or adverse effects (p=0.5) . One study comparing 4,000 IU to 2,000 IU daily found no clear difference in risk of hypertensive disorders of pregnancy (RR 2.16; 95%CI 0.68 to 6.90; low quality evidence), gestational diabetes (RR 1.53; 95%CI 0.71 to 3.28; moderate quality evidence) or preterm birth (RR 0.86; 95%CI 0.51 to 1.45; moderate quality evidence) between groups. Adverse effects were not reported. . Studies comparing doses of 1000–1200 to 2000
Do not routinely recommend testing for vitamin D status to pregnant women in the absence of a specific indication.
Approved by NHMRC in October 2017; expires October 2022
If testing is performed, only recommend vitamin D supplementation for women with vitamin D levels lower than 50 nmol/L.
Approved by NHMRC in October 2017; expires October 2022
47.3 Practice summary: vitamin D status
In the antenatal period.
- Aboriginal and Torres Strait Islander health worker
- multicultural health worker
- Take a holistic approach
Give women advice on the risks and benefits of sun exposure (see Section 47.4) and the dietary sources of vitamin D (dairy products, eggs and fish), taking cultural considerations into account.
- Document and follow-up
If a woman’s vitamin D deficiency status is tested, 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.
- Australian and New Zealand Bone and Mineral Society, the Australasian College of Dermatologists, Cancer Council Australia, Endocrine Society of Australia and Osteoporosis Australia (2016) Risks and Benefits of Sun Exposure.
- NHMRC (2006) Nutrient Reference Values for Australia and New Zealand. Canberra: National Health and Medical Research Council.
- ABS (2014a) 4727.0.55.003 - Australian Aboriginal and Torres Strait Islander Health Survey: Biomedical Results, 2012-13. Canberra: Australian Bureau of Statistics.
- ABS (2014b) 4364.0.55.006 - Australian Health Survey: Biomedical Results for Nutrients, 2011-12. Canberra: Australian Bureau of Statistics.
- ACOG (2011) ACOG Committee Opinion No. 495: Vitamin D: Screening and supplementation during pregnancy. Obstet Gynecol 118(1): 197-8.
- Asemi Z, Samimi M, Siavashani MA et al (2016) Calcium-Vitamin D Co-supplementation Affects Metabolic Profiles, but not Pregnancy Outcomes, in Healthy Pregnant Women. Int J Prev Med 7: 49.
- Bartoszewicz Z, Kondracka A, Krasnodębska-Kiljańska M et al (2013) Vitamin D insufficiency in healthy pregnancy women living in Warsaw. Ginekol Pol 84: 363–67.
- Bendall A, de Costa C, Woods C et al (2012) Vitamin D levels in pregnant women booking for antenatal care in Far North Queensland. Aust N Z J Obstet Gynaecol 52(4): 391-4.
- Binks MJ, Smith-Vaughan HC, Marsh R et al (2016) Cord blood vitamin D and the risk of acute lower respiratory infection in Indigenous infants in the Northern Territory. Med J Aust 204(6): 238.
- Bomba-Opon DA, Brawura-Biskupski-Samaha R, Kozlowski S et al (2014) First trimester maternal serum vitamin D and markers of preeclampsia. J Matern Fetal Neonatal Med 27(10): 1078-9.
- Brough L, Rees GA, Crawford MA et al (2010) Effect of multiple-micronutrient supplementation on maternal nutrient status, infant birth weight and gestational age at birth in a low-income, multi-ethnic population. Br J Nutr 104(3): 437-45.
- Burris HH, Rifas-Shiman SL, Kleinman K et al (2012) Vitamin D deficiency in pregnancy and gestational diabetes mellitus. Am J Obstet Gynecol 207(3): 182 e1-8.
- Burris HH, Thomas A, Zera CA et al (2015) Prenatal vitamin use and vitamin D status during pregnancy, differences by race and overweight status. J Perinatol 35(4): 241-5.
- Cooper C, Harvey NC, Bishop NJ et al (2016) Maternal gestational vitamin D supplementation and offspring bone health (MAVIDOS): a multicentre, double-blind, randomised placebo-controlled trial. The Lancet Diabetes & Endocrinology 4(5): 393-402.
- Dahlman I, Gerdhem P, Bergstrom I (2013) Vitamin D status and bone health in immigrant versus Swedish women during pregnancy and the post-partum period. J Musculoskelet Neoronal Interact 13(4): 464–69.
- Davies-Tuck M, Yim C, Knight M et al (2015) Vitamin D testing in pregnancy: Does one size fit all? Aust N Z J Obstet Gynaecol 55(2): 149-55.
- Dawodu A, Saadi HF, Bekdache G et al (2013) Randomized controlled trial (RCT) of vitamin D supplementation in pregnancy in a population with endemic vitamin D deficiency. J Clin Endocrinol Metab 98(6): 2337-46.
- De Laine KM, Matthews G, Grivell RM (2013) Prospective audit of vitamin D levels of women presenting for their first antenatal visit at a tertiary centre. Aust N Z J Obstet Gynaecol 53(4): 353-7.
- De-Regil LM, Palacios C, Lombardo LK et al (2016) Vitamin D supplementation for women during pregnancy. Cochrane Database Syst Rev 1: CD008873.
- Diogenes ME, Bezerra FF, Rezende EP et al (2015) Calcium Plus Vitamin D Supplementation During the Third Trimester of Pregnancy in Adolescents Accustomed to Low Calcium Diets Does Not Affect Infant Bone Mass at Early Lactation in a Randomized Controlled Trial. J Nutr 145(7): 1515-23.
- Gibson-Helm M, Teede H, Block A et al (2014) Maternal health and pregnancy outcomes among women of refugee background from African countries: a retrospective, observational study in Australia. BMC Pregnancy Childbirth 14: 392.
- Gibson-Helm M, Boyle J, Cheng IH et al (2015) Maternal health and pregnancy outcomes among women of refugee background from Asian countries. Int J Gynaecol Obstet 129(2): 146-51.
- Gidlof S, Silva AT, Gustafsson S et al (2015) Vitamin D and the risk of preeclampsia--a nested case-control study. Acta Obstet Gynecol Scand 94(8): 904-8.
- Harvey NC, Holroyd C, Ntani G et al (2014) Vitamin D supplementation in pregnancy: a systematic review. Health Technol Assess 18(45): 1-190.
- Johnson DD, Wagner CL, Hulsey TC et al (2011) Vitamin D deficiency and insufficiency is common during pregnancy. Am J Perinatol 28(1): 7-12.
- Karlsson T, Andersson L, Hussain A et al (2015) Lower vitamin D status in obese compared with normal-weight women despite higher vitamin D intake in early pregnancy. Clin Nutr 34(5): 892-8.
- Leffelaar ER, Vrijkotte TG, van Eijsden M (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. Br J Nutr 104(1): 108-17.
- Lehotay DC, Smith P, Krahn J et al (2013) Vitamin D levels and relative insufficiency in Saskatchewan. Clin Biochem 46(15): 1489-92.
- Luque-Fernandez MA, Gelaye B, VanderWeele T et al (2014) Seasonal variation of 25-hydroxyvitamin D among non-Hispanic black and white pregnant women from three US pregnancy cohorts. Paediatr Perinat Epidemiol 28(2): 166-76.
- March KM, Chen NN, Karakochuk CD et al (2015) Maternal vitamin D(3) supplementation at 50 mug/d protects against low serum 25-hydroxyvitamin D in infants at 8 wk of age: a randomized controlled trial of 3 doses of vitamin D beginning in gestation and continued in lactation. Am J Clin Nutr 102(2): 402-10.
- McAree T, Jacobs B, Manickavasagar T et al (2013) Vitamin D deficiency in pregnancy - still a public health issue. Matern Child Nutr 9(1): 23-30.
- McLeod DS, Warner JV, Henman M et al (2012) Associations of serum vitamin D concentrations with obstetric glucose metabolism in a subset of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study cohort. Diabet Med 29(8): e199-204.
- Morales E, Rodriguez A, Valvi D et al (2015) Deficit of vitamin D in pregnancy and growth and overweight in the offspring. int J Obesity 39: 61–68.
- Mutlu GY, Ozsu E, Kalaca S et al (2014) Evaluation of vitamin D supplementation doses during pregnancy in a population at high risk for deficiency. Horm Res Paediatr 81(6): 402-8.
- NICE (updated 2016) Antenatal Care for Uncomplicated Pregnancies. London: National Institute of Health and Clinical Excellence.
- Nowson CA, McGrath JJ, Ebeling PR et al (2012) Vitamin D and health in adults in Australia and New Zealand: a position statement. Med J Aust 196(11): 686-7.
- NZ MoH (2013) Companion Statement on Vitamin D and Sun Exposure in Pregnancy and Infancy in New Zealand. Wellington: Ministry of Health.
- Ozias MK, Kerling EH, Christifano DN et al (2014) Typical prenatal vitamin D supplement intake does not prevent decrease of plasma 25-hydroxyvitamin D at birth. J Am Coll Nutr 33(5): 394-9.
- Paxton GA, Teale GR, Nowson CA et al (2013) Vitamin D and health in pregnancy, infants, children and adolescents in Australia and New Zealand: a position statement. Med J Aust 198(3): 142-3.
- Perampalam S, Ganda K, Chow KA et al (2011) Vitamin D status and its predictive factors in pregnancy in 2 Australian populations. Aust N Z J Obstet Gynaecol 51(4): 353-9.
- Perumal N, Al Mahmud A, Baqui AH et al (2015) Prenatal vitamin D supplementation and infant vitamin D status in Bangladesh. Public Health Nutr: 1-9.
- RANZCOG (2015) Vitamin and Mineral Supplementation and Pregnancy. Melbourne: Royal Australian and New Zealand College of Obstetricians and Gynaecologists.
- Rodda CP, Benson JE, Vincent AJ et al (2015) Maternal vitamin D supplementation during pregnancy prevents vitamin D deficiency in the newborn: an open-label randomized controlled trial. Clin Endocrinol (Oxf) 83(3): 363-8.
- Schneuer FJ, Roberts CL, Guilbert C et al (2014) Effects of maternal serum 25-hydroxyvitamin D concentrations in the first trimester on subsequent pregnancy outcomes in an Australian population. Am J Clin Nutr 99(2): 287-95.
- Teale GR & Cunningham CE (2010) Vitamin D deficiency is common among pregnant women in rural Victoria. Aust N Z J Obstet Gynaecol 50(3): 259-61.
- Wagner CL, McNeil RB, Johnson DD et al (2013) Health characteristics and outcomes of two randomized vitamin D supplementation trials during pregnancy: a combined analysis. J Steroid Biochem Mol Biol 136: 313-20.
- Wall CR, Stewart AW, Camargo CA, Jr. et al (2016) Vitamin D activity of breast milk in women randomly assigned to vitamin D3 supplementation during pregnancy. Am J Clin Nutr 103(2): 382-8.
- Willix C, Rasmussen S, Evans S et al (2015) A comparison of vitamin D levels in two antenatal populations in regional Western Australia. Aust Fam Phys 44(3): 141–44.