Vitamins C and E and the risk of preterm birth

Most pregnancies last about 40 weeks. A premature birth takes place more than 3 weeks before the due date. Although the rate of premature birth seems to be on the rise, a healthy lifestyle helps prevent preterm labor and premature birth.

Researchers in the US collaborated to determine whether pregnant women taking vitamins C and E might lower their risk of spontaneous preterm birth.

First, the details.

  • 10,154 women, pregnant for the first time and at low risk, were randomly assigned to a treatment group from 9 to 16 weeks of gestation until delivery.
    • 1,000 mg vitamin C + 400 international units vitamin E daily
    • Placebo
  • Preterm birth attributable to premature rupture of membranes (PROM) and total spontaneous preterm births (spontaneous preterm birth attributable to PROM or spontaneous labor) were recorded.
  • Neither the women nor researchers knew the treatment given — double blind.

And, the results.

  • In women supplemented with vitamins C and E, births attributed to preterm PROM were similar at less than 37 and 35 weeks of gestation, but births were less frequent before 32 weeks of gestation.
  • However, total spontaneous preterm births across gestation in women supplemented with vitamins C and E or a placebo were similar.

The bottom line?

The authors concluded, “Maternal supplementation with vitamins C and E beginning at 9 to 16 weeks of gestation in nulliparous [never having given birth to a child] women at low risk did not reduce spontaneous preterm births.

“Low risk” women is the key to understanding this study.

Most studies report that low body mass index (BMI) is a strong risk factor for spontaneous preterm birth. Whether this relationship is due to a specific vitamin or mineral deficiency associated with low caloric consumption or to other factors is unknown. This research suggests that in the absence of risk factors, vitamin C and E supplements appear to offer no additional benefit.

8/30/10 19:42 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.