Vitamin D in pregnancy:  current concepts.
OBJECTIVE
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.


RESULTS
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.


CONCLUSIONS
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 600 IU of daily vitamin D supplementation during pregnancy to support maternal and fetal bone metabolism.
Division of Women's Primary Care, Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, North Carolina, USA. rmpera@gmail.com
Rachel P
RP
Urrutia
John M
JM
Thorp
D015519:Bone Density; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology; D011256:Pregnancy Outcome; D060728:Reproductive Health; D013472:Sunlight; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000008:administration & dosage* / Q000009:adverse effects / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology
D014807:Vitamin D; C104450:25-hydroxyvitamin D