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The effect of three dosages of supplemental vitamin D (400, 1000 and 2000 IU) on maternal and newborn 25-hydroxyvitamin D concentrations

University of British Columbia

BACKGROUND: Attaining adequate vitamin D throughout pregnancy is important for maternal and infant health. Current Canadian guidelines for vitamin D intake vary; the Recommended Dietary Allowance (RDA) set by Health Canada is 600IU/d whereas the Canadian Pediatric Society recommends 2000IU/d. At present, there is a lack of evidence as to the most appropriate intake. OBJECTIVE: To determine the effect of each of three dosages of supplemental vitamin D (400, 1000 and 2000IU) throughout pregnancy on the percentage of women achieving sufficient serum 25-hydroxyvitamin D (25OHD) defined as > 50 nmol/L and the maternal and newborn 25OHD concentrations in response to each supplementation dose. METHODS: In a randomized, double-blind, controlled trial pregnant women (n=110) were randomized to one of three doses of supplemental vitamin D³ (400, 1000 or 2000 IU) at 13-22 weeks (baseline). Participants attended a study visit at 36 weeks and infant cord blood was collected at delivery. Blood was collected for analysis for serum 25OHD at baseline and 36 weeks gestation. RESULTS: At baseline 18.2% of participants were classified as vitamin D insufficient (serum 25OHD < 50 nmol/L) with 10.9% vitamin D insufficient at 36 weeks. There were no significant differences among treatment groups in the percentage of women classified as vitamin D insufficient at 36 weeks gestation [400IU: 11%, 1000IU: 18.4%, 2000IU: 5.6%, p=0.227] or in serum 25OHD concentrations [400IU: 70.4±19.5 nmol/L, 1000IU: 76.5±25.7 nmol/L, 2000IU 80.1±20.3 nmol/L, p=0.178]. The change in serum 25OHD concentrations from baseline to 36 weeks was significantly greater in the 1000IU and 2000IU group versus the 400IU group [400IU: -0.08±15.5 nmol/L, 1000IU: 10.5±20.8 nmol/L, 2000IU:12.4±13.7 nmol/L, p=0.005] Newborn serum 25OHD concentrations did not differ across treatments [400IU: 72.2±21.4, 1000IU: 65.5±22.6, 2000IU: 91.5±19.8, p=0.111]. CONCLUSION: There were no significant differences among three dosages of supplemental vitamin D (400, 1000 and 2000IU) in the percentage of women achieving serum 25OHD > 50 nmol/L. Maternal and newborn 25OHD concentrations were not significantly different among women on the three dosages of supplemental vitamin D.

Text

2012-08-27

Attribution-NonCommercial-NoDerivs 3.0 Unported

http://hdl.handle.net/2429/43063

Human Nutrition

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/3.0/