The effect of vitamin D supplementation during pregnancy and lactation on maternal & infant 25‐hydroxyvitamin D (25OHD) concentration

Attaining adequate vitamin D status during pregnancy and lactation is important for maternal and infant health. Our objective was to determine the effect of three dose regimens of vitamin D on maternal and infant 25‐hydroxyvitamin D concentrations. 163 healthy pregnant women between 13–22 wks gestation were recruited from Vancouver, Canada and randomized to one of three doses of supplemental vitamin D3 (400 IU/d, 1000 IU/d or 2000 IU/d) to take until 8 wks postpartum. Maternal blood was collected at baseline, 36 wks gestation, and maternal and infant blood were collected 8 wks postpartum. Mean 25OHD was 68 nmol/L at baseline and 17% of participants had a 25OHD < 50 nmol/L. At 36 wks gestation, maternal serum 25OHD [mean (95%CI)] concentrations, after adjusting for baseline 25OHD, were significantly higher in the women who received 2000 IU/d [79 (75,84) nmol/L] and 1000 IU/d [78 (74, 82)] than the 400 IU/d [69 (65, 74)]. At 8 wks postpartum, maternal serum 25OHD concentrations were highest in the 2000 IU/d [88 (83, 92)] followed by the 1000 IU/d [80 (75, 84)] and the 400 IU/d [71 (67, 76)] group. Likewise, serum 25OHD concentrations were highest in infants at 8 wks whose mothers received 2000 IU/d 75 (66, 84)] followed by the 1000 IU/d [54 (45, 62)] and the 400 IU/d (44 (35, 52)]. Generally, vitamin D supplementation increased maternal and infant 25OHD concentrations in a dose response manner. (Canadian Institutes of Health Research)