Women who get little vitamin C both before and during their pregnancies have an increased risk of suffering a ruptured membrane and subsequently delivering prematurely. Vitamin C plays a role in the structure of collagen in the fetal membrane, and when it's not there, it makes the membrane weaker.

Women with a low vitamin C intake have been found to be more susceptible to premature rupture of the membrane attached to the placenta, leading to an increased risk of premature delivery. Over 2,000 women were given a questionnaire asking them to detail their intake of various foods before their pregnancy as well as during their second trimester of pregnancy.

The investigators found a strong relationship between a lack of vitamin C in a woman's diet and a tendency toward rupturing the placental membrane. For example, the women who were in the bottom 10th percentile of vitamin C consumers before pregnancy, meaning they took in less than 21 milligrams (mg) of vitamin C daily, had twice the risk of suffering a premature ruptured membrane during their pregnancy. Similarly, women who were in the bottom 10th percentile of vitamin C users during their second trimester of pregnancy, consuming less than 65 mg of vitamin C daily, were at 70% increased risk of suffering a premature ruptured membrane.

The researchers found that only 28% of the women said they had taken vitamin C supplements before pregnancy, while 80% reported taking a multivitamin by the 30th week of pregnancy. The study's results suggest that starting vitamins after becoming pregnant is not enough to ward off rupture risk.

Annual Meeting of the Society for Maternal-Fetal Medicine's in New Orleans, Louisiana January 18, 2002