December 23, 2008 — Vitamin D deficiency in pregnancy is associated with increased odds of primary cesarean delivery, according to the results of a study reported in the December 23 Online First issue of the Journal of Clinical Endocrinology & Metabolism.

“At the turn of the 20th century, women commonly died in childbirth due to ‘rachitic pelvis,’ ” write Anne Merewood, MPH, IBCLC, from Boston University School of Medicine in Massachusetts, and colleagues. “Although rickets virtually disappeared with the discovery of the hormone ‘vitamin’ D, recent reports suggest vitamin D deficiency is widespread in industrialized nations. Poor muscular performance is an established symptom of vitamin D deficiency, [and] the current US caesarean birth rate is at an all-time high of 30.2%.”

The objective of this study was to determine the relationship between maternal serum 25-hydroxyvitamin D [25(OH)D] levels and the rate of primary cesarean delivery.

At an urban teaching hospital in Boston, with 2500 births per year, the investigators measured maternal and infant serum 25(OH)D at birth in 253 mother-infant pairs, of whom 43 (17%) had a primary cesarean delivery. Demographic and medical data were abstracted from the maternal medical record.

The rate of cesarean delivery was 14% in women with 25(OH)D levels of 37.5 nmol/L or higher and 28% in women with serum 25(OH)D levels less than 37.5 nmol/L (P = .012). The risk for cesarean delivery was nearly 4-fold higher in women with 25(OH)D levels less than 37.5 nmol/L vs those with 25(OH)D levels of 37.5 nmol/L or more, based on multivariable logistic regression analysis controlling for race, age, educational level, insurance status, and alcohol use (adjusted odds ratio [OR], 3.84; 95% confidence interval [CI], 1.71 – 8.62).

Limitations of this study include sample too small to determine whether vitamin D deficiency is related to specific types of cesarean deliveries, such as cephalopelvic disproportion or failure to progress.

“Vitamin D deficiency was associated with increased odds of primary caesarean section,” the study authors write. “A randomized clinical trial is now needed to determine if adequate vitamin D supplementation during pregnancy to raise blood levels above 37.5 nmol/L can reduce the caesarean section rate.”

The US Department of Health and Human Services; Bureau of Maternal Child Health; and the US Department of Agriculture Cooperative State Research, Education, and Extension Service supported this study. The study authors have disclosed no relevant financial relationships.

J Clin Endocrinol Metab. Published online December 23, 2008.


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