Article Review: Vitamin D deficiency in pregnancy may be linked to an increased risk of cesarean delivery according to results published in the online Journal of Clinical Endocrinology & Metabolism on December 23, 2008. The study was performed in a Boston urban teaching hospital. The objective of the study was to determine the relationship between maternal serum levels of 25-hydroxyvitamin D [25(OH)D] and rate of primary cesarean delivery (i.e. a woman who delivers by cesarean section for the first time).
The rate of cesarean delivery in the United States is 30.2%; only 17% of the woman at this institution had cesarean deliveries. In two years 253 woman-infant pairs were enrolled in the study; 43 delivered by primary cesarean section. A serum level of 25-hydroxyvitamin D less than 15 ng/ml (i.e. 37.5 nmol/L) within 72 hours of delivery doubled the risk of a cesarean delivery when compared to women with 25(OH)D levels greater than 15 ng/ml.
Discussion
Vitamin D deficiency is defined by the Centers for Disease Control as a serum level of less than 15 ng/ml (37.5 nmol/L).
Vitamin D is naturally available in very few foods such as fish and fish liver oils while beef liver, cheese, egg yolks and some mushrooms have small amounts. Milk, breakfast cereals and some brands of orange juice, yogurt and margarine are fortified with Vitamin D. Though cod liver oil remains the best natural source of Vitamin D, it also contains more than 10,000 IU of Vitamin A - an amount when taken daily during pregnancy may cause birth defects. Vitamin D is produced in the body when skin is exposed to the sun. However, the most reliable form of Vitamin D is available as a supplement.
Adequate Vitamin D (a serum level yet to be determined) contributes to bone health, a reduction in inflammation, and may also decrease an individuals risk of cancer, diabetes, hypertension, glucose intolerance, multiple sclerosis and other medical conditions. Groups at risk for vitamin D inadequacy include breastfed infants, adults greater than 50, people with dark skin, people with limited sun exposure, those with fat malabsorption or who are obese.
Adequate scientific data is not available at this time for recommendations on suggested daily intake, a number of studies are currently underway to answer this question. Tolerable upper intake Levels (UL) of vitamin D for pregnant women is 2000 IU (50 mcg). However, several nutrition scientists have recently challenged this UL, first published in 1997.
For now, the Food and Nutrition Board at the Institute of Medicine cites 200 IU as an adequate daily intake for women of reproductive age. However, these recommendations may soon change in light of ongoing research.
Other articles recently published articles about vitamin D:
1. What Is the Effect of Vitamin D Deficiency During Pregnancy?
2. Maternal Vitamin D Deficiency May Increase Risk for Preeclampsia
3. Vitamin D Deficiency: Implications Across the Lifespan
4. American Academy of Pediatrics Updates Guidelines for Vitamin D Intake
References:
1. J Clin Endocrin Metab. First published ahead of print December 23, 2008 as doi:10.1210/jc.2008-1217
2. Dietary Supplement Fact Sheet: Vitamin D published by the National Institutes of Health - Office of Dietary Supplements
3. Vitamin D Deficiency Linked to Greater Risk for Primary Cesarean Delivery. Medscape Medical News.
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