Low Vitamin D Increases Risk for Preterm Birth

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Low Vitamin D Increases Risk for Preterm Birth
Low Vitamin D Increases Risk for Preterm Birth

(HealthDay News) — Women who have low blood levels of vitamin D during pregnancy are more likely to give birth prematurely, new research suggests. The study was published in Obstetrics & Gynecology.

Lisa Bodnar, PhD, associate professor of epidemiology and obstetrics and gynecology at the University of Pittsburgh, and colleagues looked at 2,123 women who didn't give birth early, and 1,126 who delivered preterm. 

All of the women included in the research had given birth to single infants between 1999 and 2010. The researchers grouped the women as having serum 25-hydroxyvitamin D (25[OH]D) of less than 50 nmol/L, 50 nmol/L to 74.9 nmol/L and 75 nmol/L or above.

The researchers found that women with the lowest levels of vitamin D were about 1.5 times as likely to deliver early compared with those with the highest levels. 

Before adjusting for other preterm birth risks, the researchers found that 11.3% of the mothers in the lowest vitamin D level group delivered before 37 weeks. About 9% of mothers (8.6%) in the middle group delivered early and 7.3% of those in the highest level group delivered early. 

When the researchers adjusted the data to account for other preterm birth risk factors, they saw a similar association between lower vitamin D levels and preterm birth.

"Mothers who were deficient in vitamin D in early parts of pregnancy were more likely to deliver early, preterm, than women who did not have vitamin D deficiency," Bodnar told HealthDay

Vitamin D may provide benefit by helping to reduce bacterial infection in the placenta, which can trigger an early delivery, she said.


  1. Bodnar LM et al. Obstet Gynecol. 2015;doi:10.1097/AOG.0000000000000621.
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