Background The need, safety and effectiveness of vitamin D supplementation during pregnancy remain controversial. Design In this randomized controlled trial, women with a singleton pregnancy at 12–16 weeks’ gestation received 400, 2000 or 4000 IU vitamin D3/day until delivery. The primary outcome was maternal/neonatal circulating 25(OH)D at delivery, with secondary outcomes 25(OH)D ≥80 nmol/L achieved and 25(OH)D concentration required to achieve maximal 1,25(OH)2D production. Results Of the 494 women enrolled, 350 women continued until delivery: Mean 25(OH)D by group at delivery and 1-month before delivery were significantly different (p<0.0001), and percent who achieved sufficiency was significantly different by group, greatest in 4000 IU group (p<0.0001). The relative risk (RR) for achieving ≥80 nmol/L within one month of delivery was significantly different between 2000 vs. 400 IU (RR 1.52 [CI 1.24–1.86]); 4000 vs. 400 (RR 1.60 [CI 1.32–1.95]), but not between 4000 vs. 2000 (RR 1.06 [CI 0.93–1.19]). Circulating 25(OH)D had a direct influence on circulating 1,25(OH)2D concentrations throughout pregnancy (p<0.0001) with maximal production of 1,25(OH)2D in all strata in the 4000 IU group. There were no differences between groups on any safety measure. Not a single adverse event was attributed to vitamin D supplementation or circulating 25(OH)D levels. Conclusions Vitamin D supplementation of 4,000 IU/day for pregnant women was safe and most effective in achieving sufficiency in all women and their neonates regardless of race while the current estimated average requirement was comparatively ineffective at achieving adequate circulating 25(OH)D, especially in African Americans.

With limited sun exposure, an intake of 400 IU/day vitamin D(3) did not sustain circulating maternal 25(OH)D levels, and thus, supplied only extremely limited amounts of vitamin D to the nursing infant via breast milk. Infant levels achieved exclusively through maternal supplementation were equivalent to levels in infants who received oral vitamin D supplementation. Thus, a maternal intake of 6400 IU/day vitamin D elevated circulating 25(OH)D in both mother and nursing infant.

OBJECTIVE: Compare effectiveness of maternal vitamin D 3 supplementation with 6400 IU per day alone to maternal and infant supplementation with 400 IU per day.METHODS: Exclusively lactating women living in Charleston, SC, or Rochester, NY, at 4 to 6 weeks postpartum were randomized to either 400, 2400, or 6400 IU vitamin D 3 /day for 6 months. Breastfeeding infants in 400 IU group received oral 400 IU vitamin D 3 /day; infants in 2400 and 6400 IU groups received 0 IU/day (placebo). Vitamin D deficiency was defined as 25-hydroxy-vitamin D (25(OH)D) ,50 nmol/L. 2400 IU group ended in 2009 as greater infant deficiency occurred. Maternal serum vitamin D, 25(OH)D, calcium, and phosphorus concentrations and urinary calcium/creatinine ratios were measured at baseline then monthly, and infant blood parameters were measured at baseline and months 4 and 7.RESULTS: Of the 334 mother-infant pairs in 400 IU and 6400 IU groups at enrollment, 216 (64.7%) were still breastfeeding at visit 1; 148 (44.3%) continued full breastfeeding to 4 months and 95 (28.4%) to 7 months. Vitamin D deficiency in breastfeeding infants was greatly affected by race. Compared with 400 IU vitamin D 3 per day, 6400 IU/day safely and significantly increased maternal vitamin D and 25(OH)D from baseline (P , .0001). Compared with breastfeeding infant 25(OH)D in the 400 IU group receiving supplement, infants in the 6400 IU group whose mothers only received supplement did not differ. CONCLUSIONS:Maternal vitamin D supplementation with 6400 IU/day safely supplies breast milk with adequate vitamin D to satisfy her nursing infant's requirement and offers an alternate strategy to direct infant supplementation. WHAT'S KNOWN ON THIS SUBJECT:The vitamin D concentration in breast milk of women taking 400 IU vitamin D per day is relatively low, leading to vitamin D deficiency in breastfeeding infants. As a result, the American Academy of Pediatrics recommends breastfeeding infant vitamin D supplementation within days after birth. WHAT THIS STUDY ADDS:Maternal vitamin D supplementation alone with 6400 IU/day safely supplies breast milk with adequate vitamin D to satisfy the requirement of her nursing infant and offers an alternate strategy to direct infant supplementation. Dr Hollis, as the principal investigator (PI) of the project, worked with Dr Wagner in the conception of the project, study design, implementation of the study, laboratory analyses, data analyses, and writing of the manuscript; Dr, Wagner as clinical PI of the study, worked with Drs Hollis and Howard, site PI at the University of Rochester (U of R), and all other coinvestigators in the conception of the project, study design, implementation of the study, review of clinical and laboratory data, subject safety, data analyses, and writing of the manuscript; Dr Howard as clinical site PI at the U of R worked directly with Dr Wagner; she was involved in the conception of the project, study design, implementation of the study, laboratory analyses, data analyses, and writing of the manuscript; M...

The objective was to determine the incidence of vitamin D deficiency, insufficiency, and sufficiency in African-American, Hispanic, and Caucasian pregnant women. Blood samples were taken from 154 African-American, 194 Hispanic, and 146 Caucasian women at <14 weeks of gestation; 25 hydroxyvitamin D levels (25(OH)D) levels were measured by radioimmunoassay. The mean 25(OH)D levels in African-American, Hispanic, and Caucasian pregnant women were 15.5 ± 7.2 (standard deviation), 24.1 ± 8.7, 29.0 ± 8.5 ng/mL, respectively. Ninety-seven percent of African-Americans, 81% of Hispanics, and 67% of Caucasians were deficient (25(OH)D levels <20 ng/mL or <50 nmol/L) or insufficient (25(OH)D levels ≥ 20 ng/mL or <32 ng/mL or ≥ 50 nmol/L or <80 nmol/L). Of these pregnant women, 82% had vitamin D levels <32 ng/mL (<80 ng/mL). In logistic regression models, race was the most important risk factor for vitamin D deficiency or insufficiency. African-American women and Hispanic women were more likely to have vitamin D insufficiency and deficiency than Caucasian women. Furthermore, primigravid women were more at risk for vitamin D insufficiency. This study demonstrates widespread vitamin D deficiency and insufficiency in pregnant females living at a southern latitude. African-Americans are at greatest risk.

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