A new study published in The Journal of Nutrition found that most women with gestational diabetes had adequate vitamin D status.  Furthermore, if maternal multivitamin supplementation regimens were adhered to, newborn vitamin D status was not complicated by gestational diabetes.

In pregnancies complicated by gestational diabetes, vitamin D status of the newborn is often compromised. However, with high adherence to multivitamin use during pregnancy, blood vitamin D concentration of infants born to a mother with gestational diabetes is typically within the healthy sufficient range (>50 nmol/L). To date, the proportion of infants born to mothers with gestational diabetes with vitamin D blood levels within or above the suggested range has not been reported in Canada. 

Canadian prenatal nutrition guidelines advise all women who could become pregnant or who are pregnant to take a multivitamin containing 400 IU vitamin D.  This amount has also been shown to build vitamin D stores during infancy. However, guidelines for infant supplementation with vitamin D do not specifically address the needs of infants born to mothers with gestational diabetes.

To better understand the impact of a pregnancy complicated by gestational diabetes, researcher Hope Weiler (Health Canada) and colleagues (McGill University) assessed vitamin D status in infants of mothers with gestational diabetes, and compared vitamin D status in response to 400 vs. 1000 IU/day vitamin D supplementation in a subset of infants with low (<50 nmol/L) blood vitamin D levels.

Blood levels of vitamin D were measured in infants of mothers with gestational diabetes and categorized as deficient or adequate. Breastfed infants with blood vitamin D levels <50 nmol/L at birth were randomly assigned to 400 or 1000 IU/day of supplemental vitamin D. Blood levels of vitamin D were measured at baseline (<1 month) and 3, 6, and 12 months of age. The mean newborn blood vitamin D level was 46.6 nmol/L, with 15.3% < 30 nmol/l and 61.2% >40 nmol/L.  Most infants that were randomly assigned to receive 400 or 1000 IU of supplemental vitamin D/day were breastfed to 3 months (79.9% and 75.0%, respectively). Mean infant blood vitamin D levels were higher in the 1000-IU/day group at 3 months, and although not different at 6 and 12 months, levels were maintained at >50nmol/L. 

In this study, infants of women with gestational diabetes had, on average, adequate vitamin D status. In those born with blood vitamin levels <50 nmol/L, vitamin D status was corrected by 3 months of age in response to 400 or 1000 IU/day of supplemental vitamin D.  Collectively, study results suggest that newborn vitamin D status is not impacted in pregnancies complicated by gestational diabetes if maternal multivitamins are adhered to, and that neonatal response to supplementation with 400 IU/day is adequate. Thus, dietary guidance should continue to recommend that all women who could become pregnant take a multivitamin supplement and that breastfed infants receive 400 IU/day of supplemental vitamin D.


Hope A Weiler, Atheer Attar, Zahra Farahnak, Olusola F Sotunde, Maryam Razaghi, Nathalie Gharibeh, Ali Khamessan, Catherine A Vanstone, Vitamin D Status of Infants of Mothers with Gestational Diabetes: Status at Birth and a Randomized Controlled Trial of Vitamin D Supplementation across Infancy, The Journal of Nutrition, Volume 152, Issue 11, November 2022, Pages 2441–2450, https://doi.org/10.1093/jn/nxac194.

Images via canva.com.