Maternal vitamin D supplementation during pregnancy prevents vitamin D deficiency in the newborn: an open-label randomized controlled trial.

OBJECTIVE To determine whether maternal vitamin D supplementation, in the vitamin D deficient mother, prevents neonatal vitamin D deficiency. DESIGN Open-label randomized controlled trial. SETTING Metropolitan Melbourne, Australia, tertiary hospital routine antenatal outpatient clinic. PARTICIPANTS Seventy-eight women with singleton pregnancies with vitamin D deficiency/insufficiency (serum 25-OH Vit D < 75 nmol/l) at their first antenatal appointment at 12-16-week gestation were recruited. INTERVENTION Participants were randomized to vitamin D supplementation (2000-4000 IU cholecalciferol) orally daily until delivery or no supplementation. MAIN OUTCOME MEASURES The primary outcome was neonatal serum 25-OH vit D concentration at delivery. The secondary outcome was maternal serum 25-OH vit D concentration at delivery. RESULTS Baseline mean maternal serum 25-OH vit D concentrations were similar (P = 0·9) between treatment (32 nmol/l, 95% confidence interval 26-39 nmol/l) and control groups (33 nmol/l, 95% CI 26-39 nmol/l). Umbilical cord serum 25-OH vit D concentrations at delivery were higher (P < 0·0001) in neonates of treatment group mothers (81 nmol/l, 95% CI; 70-91 nmol/l) compared with neonates of control group mothers (42 nmol/l, 95% CI; 34-50 nmol/l) with a strongly positive correlation between maternal serum 25-OH Vit D and umbilical cord serum 25-OH vit D concentrations at delivery (Spearman rank correlation coefficient 0·88; P < 0·0001). Mean maternal serum 25-OH Vit D concentrations at delivery were higher (P < 0·0001) in the treatment group (71 nmol/l, 95% CI; 62-81 nmol/l) compared with the control group (36 nmol/l, 95% CI; 29-42 nmol/l). CONCLUSION Vitamin D supplementation of vitamin D deficient pregnant women prevents neonatal vitamin D deficiency.