For women who’ve previously had a preterm delivery, having sex during early pregnancy does not affect the likelihood of having another preterm birth, new research shows.

Cutting back on physical activity, including sexual intercourse, during pregnancy is often recommended to prevent or treat preterm labor symptoms, note the authors of the study in the medical journal Obstetrics and Gynecology. Women with a prior preterm birth are known to be at increased risk for having a recurrence and, therefore, could be prime targets for such advice.

Still, data are lacking on the effect of sexual intercourse on the risk of recurrent preterm delivery.

Dr. Nicole P. Yost, from Emory University School of Medicine in Atlanta, and colleagues looked at the effect of sexual intercourse on the risk of preterm birth in 187 pregnant women who had a previous preterm birth.

The women’s sexual history was obtained at 16 to 18 weeks into their pregnancy by a research nurse. Data from 165 of the women were available for analysis.

Thirty-six percent of the women had a spontaneous preterm birth - that is, at less than 37 weeks - the report indicates.

The incidence of recurrent preterm birth among women reporting some sexual intercourse during pregnancy was 38 percent - higher, but not significantly different from the 28 percent rate seen in women who reported little or no intercourse during pregnancy.

Dr. Jeanne Sheffield, an obstetrician-gynecologist not affiliated with the study, told Reuters Health that although many doctors recommend against sexual intercourse during pregnancy, “every large study that has looked at coitus and preterm labor has not found an association.”

The message from the study is that sexual intercourse during pregnancy is probably okay for women who have a history of preterm birth, said Sheffield, a professor at UT Southwestern Medical Center at Dallas.

“A possible exception,” she advised, “is the small group of women who have a cerclage (reinforcement of the opening of the cervix) in place, ruptured membranes, or are already dilated and still preterm. For these women, we often recommend decreasing or abstaining from sexual intercourse.”

SOURCE: Obstetrics and Gynecology, April 2006.