Date of Award

January 2013

Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Cindy M. Anderson


In the United States, at least 50% of breastfeeding mothers are vitamin D deficient, increasing risk for vitamin D deficiency in exclusively breastfed infants. A gap in knowledge exists regarding best practices in maternal vitamin D supplementation during pregnancy and lactation that will yield adequate infant vitamin D levels. The objective of this study was to identify the combined effect of maternal prenatal and postnatal vitamin D supplementation on vitamin D transfer to exclusively breastfed infants. Additionally, due to the immune modulating effects of vitamin D, maternal pro- and anti-inflammatory cytokines were measured across pregnancy and the postpartum. A double-blind, randomized controlled trial design was used. A total of 16 pregnant women were enrolled in the study at 24-28 weeks gestation. The control group (N= 6) received a prenatal vitamin containing vitamin D 400 IU daily plus a placebo void of vitamin D. The experimental group (N=7) received the same prenatal vitamin plus a capsule containing 3400 IU vitamin D, for a total of 3800 IU daily. Participants continued their assigned supplements through 4-6 weeks of lactation. Pertinent pregnancy, delivery, and postnatal health data were collected on maternal and infant participants. Serum levels of 25-hydroxyvitamin D were measured in maternal participants at enrollment and in both maternal and infant participants at delivery and after 4-6 weeks of lactation. Maternal plasma TNF-alpha, IL-6, and IL-10 were measured at enrollment, delivery and 4-6 weeks of lactation. There was a significant effect of maternal vitamin D supplementation on maternal 25-hydroxyvitamin D at delivery (p=0.044) and at 4-6 weeks of lactation (p=0.002). A significant difference in the infant participant groups at delivery was also found (p=0.017), however this was not significant at 4-6 weeks of lactation (p=0.256). Controlling for maternal baseline using repeated measures techniques, the overall effect of maternal vitamin D supplementation on infant 25-hydroxyvitamin D approached significance (p=0.065). There was no impact of vitamin D supplementation on maternal cytokine production. This study adds novel information regarding the impact of continuous prenatal to postpartum maternal vitamin D supplementation on the vitamin D status of exclusively breastfed infants.