The effect of vitamin D supplementation during pregnancy and lactation on maternal & infant 25-hydroxyvitamin D concentration

BACKGROUND: Adequate vitamin D during pregnancy and lactation is important for optimal health of mother and infant. Due to low levels of vitamin D occurring in breast milk, exclusively breastfed infants are recommended by Health Canada to be supplemented with 400 IU/day of vitamin D. A potential solution to this is maternal vitamin D supplementation during pregnancy and lactation to raise maternal, infant serum 25-hydroxyvitamin D (25OHD) and breast milk vitamin D content. OBJECTIVE: To determine the effect of three dose regimens of supplemental vitamin D (400 IU/d, 1000 IU/d and 2000 IU/d) during pregnancy and lactation on maternal and infant 25-hydroxyvitamin D concentrations at 8 weeks post-partum. METHODS: In a double-blind, randomized controlled trial healthy pregnant women (n=226) between 13-24 weeks of gestation were recruited from Vancouver, Canada and randomized to take one of three doses of supplemental vitamin D3 (400 IU/d, 1000 IU/d or 2000 IU/d) until 8 weeks postpartum. Maternal blood was collected at baseline, 36 weeks gestation, and maternal and infant blood were collected 8 weeks postpartum. RESULTS: Mean 25OHD was 66 nmol/L at baseline and 21% of participants had a 25OHD < 50 nmol/L. At 8 weeks postpartum, maternal serum 25OHD concentrations [mean (95% CI)] were highest in the 2000 IU/d [87 (83, 90) nmol/L] followed by the 1000 IU/d [78 (74,81) nmol/L] and the 400 IU/d [69 (66, 73) nmol/L] group using intent to treat analysis. Likewise, at 8 weeks serum 25OHD concentrations were highest in infants whose mothers received 2000 IU/d [75 (67, 83 nmol/L)] followed by the 1000 IU/d [52 (45, 58) nmol/L] and the 400 IU/d [45 (38,52) nmol/L]. CONCLUSION: Maternal vitamin D supplementation of 2000 IU/d during pregnancy and lactation was found to be protective against vitamin D deficiency in infants for the first two months after birth. Generally, vitamin D supplementation increased maternal and infant 25OHD concentrations in a dose response manner.Land and Food Systems, Faculty ofGraduat