Vitamin D in pregnancy: current concepts
Rachel P. Urrutia and John M. Thorp
Curr Opin Obstet Gynecol. 2012 Feb 9.
Purpose of review: Vitamin D is part of a complex steroid hormone system long known to be involved in bone metabolism. Recently, vitamin D has been implicated in physiologic processes as diverse as vascular health, immune function, metabolism and placental function. This review summarizes the current evidence for the role of vitamin D in pregnancy and perinatal outcomes A systematic review of articles published in PubMed between May 2010 and October 2011 was undertaken using key words for vitamin D and pregnancy. Seventy-eight studies were reviewed.
Recent findings The biologic evidence regarding a role for vitamin D in reproductive outcomes is strong, and rates of vitamin D deficiency may be high among pregnant women. However, no consensus exists regarding optimum vitamin D levels in pregnancy or standard measurement of vitamin D deficiency. Clinical studies establishing an association between vitamin D levels and adverse pregnancy outcomes such as preeclampsia, gestational diabetes, low birthweight, preterm labor, cesarean delivery and infectious diseases have conflicting results. This is likely due to a paucity of randomized trials, heterogeneity of populations studied and low sample size with poor adjustment for confounding among observational studies.
Summary Further research should focus on defining optimum 25-hydroxy vitamin D levels in pregnancy as well as among various subgroups of the population. Randomized trials are needed to determine whether vitamin D supplementation can improve pregnancy outcomes. Currently, the American College of Obstetrics and Gynecology and the Institute of Medicine recommend 600IU of daily vitamin D supplementation during pregnancy to support maternal and fetal bone metabolism.
KEY POINTS
- Vitamin D is involved in reproductive health.
- Optimal vitamin D levels in pregnancy are unknown.
- No conclusive evidence links lower levels of 25-hydroxy vitamin D with adverse pregnancy outcomes.
- Pregnant women should receive 600IU of vitamin D supplementation daily.
"Only one negative trial is reported in the literature, and the dose was 400 IU."
PMID 22327734
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Observation by VitaminDWiki
Literature review looked in depth at 75 articles from May 2010 to Nov 2011
Reviewers were not convinced that more vitamin D is needed.
They appeared to ignore the group of pregnant women who are doubly at risk of being vitamin D deficient - those with dark skins
The IoM recommendation of Nov 2010 was based on publications before 2009.