Vitamin D in pregnancy: current concepts.
ABSTRACT 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.
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.
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.
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ABSTRACT: The essentiality of vitamin D for normal growth and development has been recognized for over 80 years, and vitamin D fortification programs have been in place in the United States for more than 70 years. Despite the above, vitamin D deficiency continues to be a common finding in certain population groups. Vitamin D deficiency has been suggested as a potential risk factor for the development of preeclampsia, and vitamin D deficiency during infancy and early childhood is associated with an increased risk for numerous skeletal disorders, as well as immunological and vascular abnormalities. Vitamin D deficiency can occur through multiple mechanisms including the consumption of diets low in this vitamin and inadequate exposure to environmental ultraviolet B rays. The potential value of vitamin D supplementation in high-risk pregnancies and during infancy and early childhood is discussed. Currently, there is vigorous debate concerning what constitutes appropriate vitamin D intakes during early development as exemplified by differing recommendations from the Institute of Medicine Dietary Reference Intake report and recent recommendations by the Endocrine Society. As is discussed, a major issue that needs to be resolved is what key biological endpoint should be used when making vitamin D recommendations for the pregnant woman and her offspring. Birth Defects Research (Part C) 99:24-44, 2013. © 2013 Wiley Periodicals, Inc.Birth Defects Research Part C Embryo Today Reviews 01/2013; 99(1):24-44. DOI:10.1002/bdrc.21031 · 3.87 Impact Factor
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ABSTRACT: Vitamin D has garnered a great deal of attention in recent years due to a global prevalence of vitamin D deficiency associated with an increased risk of a variety of human diseases. Specifically, hypovitaminosis D in pregnant women is highly common and has important implications for the mother and lifelong health of the child, since it has been linked to maternal and child infections, small-for-gestational age, preterm delivery, preeclampsia, gestational diabetes, as well as imprinting on the infant for life chronic diseases. Therefore, factors that regulate vitamin D metabolism are of main importance, especially during pregnancy. The hormonal form and most active metabolite of vitamin D is calcitriol. This hormone mediates its biological effects through a specific nuclear receptor, which is found in many tissues including the placenta. Calcitriol synthesis and degradation depend on the expression and activity of CYP27B1 and CYP24A1 cytochromes, respectively, for which regulation is tissue specific. Among the factors that modify these cytochromes expression and/or activity are calcitriol itself, parathyroid hormone, fibroblast growth factor 23, cytokines, calcium and phosphate. This review provides a current overview on the regulation of vitamin D metabolism, focusing on vitamin D deficiency during gestation and its impact on pregnancy outcomes.Nutrients 01/2015; 7(1):443-480. DOI:10.3390/nu7010443 · 3.15 Impact Factor
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ABSTRACT: Objective: To evaluate the association of maternal serum 25-hydroxyvitamin D (25[OH]D) status with glucose homeostasis and obstetric and newborn outcomes in women screened for gestational diabetes mellitus (GDM).Methods: Consecutive women were screened for GDM at 24 to 28 weeks' gestation during the months of maximal sunlight exposure in Spain (June through September). Serum 25(OH)D levels and parameters of glucose homeostasis were measured. Outcomes of the delivery and newborn were collected.Results: Two hundred sixty-six women were screened. Vitamin D deficiency (25[OH]D <20 ng/mL) was observed in 157 women (59%). We observed an inverse correlation between 25(OH)D levels and hemoglobin A1c, homeostasis model assessment of insulin resistance, serum insulin, and fasting and 1-hour oral glucose tolerance test glucose levels (P<.001). With a 25(OH)D concentration less than 20 ng/mL, the odds ratios were 3.31 for premature birth (95% confidence interval, 1.52-7.19; P<.002) and 3.93 for cesarean delivery (95% confidence interval, 2.00-7.73; P<.001). A 25(OH)D concentration of 20 ng/mL had 79% sensitivity and 51% specificity for cesarean delivery and 80% sensitivity and 45% specificity for premature birth. The cutoffs with the best combination of sensitivity and specificity were 16 ng/mL for cesarean delivery (62.9% sensitivity and 61.2% specificity) and 14 ng/mL for premature birth (66.7% sensitivity and 71.0% specificity).Conclusions: In the population we sampled, vitamin D deficiency is very common during pregnancy. Lower 25(OH)D levels are associated with disorders of glucose homeostasis and adverse obstetric and newborn outcomes.Endocrine Practice 05/2012; 18(5):676-84. DOI:10.4158/EP12025.OR · 2.59 Impact Factor