Vitamin D Levels May Raise Preterm Birth Risk

Vitamin D may play a bigger role in pregnancy than simply supporting bone health.

A new study suggests that optimizing vitamin D levels before and during pregnancy may improve outcomes for both mother and baby, including the risk of preterm birth.

“We learn about vitamin D’s role in bone health, but no one teaches us about the various roles in pregnancy, especially this relationship with preterm birth we are uncovering,” said study author Anjali Borsum, a student at the Medical University of South Carolina College of Medicine in Charleston.

An analysis of more than 15,000 pregnancies found that women with the lowest vitamin D levels had the highest risk of preterm birth — defined as delivery before 37 weeks.

The link was especially pronounced in very preterm births — those occurring before 32 weeks.

Researchers say randomized clinical trials are needed to determine whether optimizing vitamin D during pregnancy can reduce the risk of this complication.

In the meantime, the authors said women who get limited exposure to the sun may want to talk to their healthcare provider about their vitamin D levels and potential supplementation.

Prior research by members of the same team suggests vitamin D may also help with development of the placenta and reduce the risk of other serious pregnancy complications such as preeclampsia and gestational diabetes.

The study was published in the Journal of Perinatology.

More information

The American Pregnancy Association has more on vitamins and pregnancy.

SOURCE: HealthDay TV, Sept. 21, 2026