COLUMBUS, Ohio - Despite a widely believed old wives' tale, having sex near the end of pregnancy won't speed up the start of labor. In fact, a new study shows, it might even delay the birth by a few days.
COLUMBUS, Ohio, June 2 - Despite a widely believed old wives' tale, having sex near the end of pregnancy won't speed up the start of labor.
In fact, it might even delay labor onset for a few days, according to research here.
"Patients may continue to hear the 'old wives' tale' that intercourse will hasten labor, but according to this data, they should not hear it from the medical community," said Jonathan Schaffir, M.D., of the Ohio State Medical Center here.
"Many pregnant women (and some physicians) believe that sexual intercourse at term will hasten the onset of labor," Dr. Schaffir noted in the June issue of Obstetrics & Gynecology. To test the issue, he enrolled 95 women in a study evaluating the effect of intercourse in the weeks before delivery.
Over the one-year period from July 2004 to July 2005, women with a low-risk pregnancy were asked to take part in the study at the next office visit after they finished their 37th week. All 95 of the women who were approached agreed to take part but two delivered at another institution and were not included in the data analysis.
Overall, Dr. Schaffir said, slightly 47 of 93 of the women (50.5%) reported having sex at some point over the final few weeks of their pregnancy. That proportion is larger than the 26% found in the largest study of sexual behavior in pregnancy, he said.
But the sex didn't bring the pregnancy to term more quickly: The sexually active women delivered their babies at an average gestational age of 39.9 weeks, compared with 39.3 weeks in the abstinent group. The difference, about four days, was statistically significant at P=0.001, but not clinically significant, Dr. Schaffir said.
Dr. Schaffir also calculated Bishop scores to judge the effect of intercourse on cervical ripening; the theory was that prostaglandins in semen, and possibly the physical effects of intercourse and orgasm, might make the cervix more favorable.
However, he said, there was no significant effect, either for any intercourse or for frequency of intercourse.
The study had some limitations, Dr. Schaffir said. For one thing, the study was retrospective, depending on reports from the women at each office visit and after birth. The details of the sexual activity are also not analyzed, including such things as "degree of arousal and engorgement, presence of orgasm, and possibility of multiple orgasms," he said.
Also, there's the possibility that just being enrolled in the study might have inspired some of the women to try sex during the last weeks of pregnancy when they might otherwise not have done so.
While there's no apparent morbidity associated with having sex late in pregnancy, Dr. Schaffir said, there's also no data suggesting that physicians should recommend it.