Vitamin D deficiency is common during pregnancy, especially among high-risk women, including vegetarians, those with little sun exposure, and members of ethnic minorities, according to the American College of Obstetrician and Gynecologists.

A new study included 93 pregnant women whose vitamin D levels were checked before childbirth and who received an epidural for pain during labor.

The researchers measured how much pain medication each of the women required during delivery.

Women with lower vitamin D levels required significantly more pain medication than those with higher vitamin D levels, according to the study.