Why does sex bring on labor

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Please review the Terms of Use before using this site. Tan said that many women believe intercourse can induce labor, and scientists have proposed plausible biological explanations for why it might help. For one, semen contains a hormonelike substance called prostaglandin, which is used in synthetic form to induce labor.

Breast stimulation is also thought to hasten labor and orgasm can trigger uterine contractions. Tan said the belief also probably came from "the deep seated folk perception that intercourse in pregnancy may be unsafe and may cause pregnancy expulsion or miscarriage despite fairly replete evidence to the contrary.

But few studies have ever investigated whether sex really can initiate labor, and the small amount of existing evidence was inconclusive, Tan and his colleagues write in the obstetrics and gynecology journal BJOG. So they set out to see whether advising women to have sex during the final weeks of pregnancy could help them avoid an induction. The researchers invited more than 1, women to participate, all of whom were 35 to 38 weeks pregnant the typical pregnancy lasts 40 weeks and none of whom had had sex in the previous six weeks.

Roughly half of the women were advised by a physician to have sex frequently as a means of safely expediting labor. The other half were told that sex was safe during pregnancy, but that its effects on labor were unknown. Having sex will not cause labor to begin before your body is ready for delivery. Instead, the prostaglandins, uterine contractions, and oxytocin may simply augment the processes that are already at work whether you realize it or not.

In a study , researchers asked women to keep a record of sexual activity after they had reached 36 weeks of gestation. Some women completed diaries. The results showed that the women who were sexually active at term did tend to deliver sooner than those who did not have sex. Not only that, but the need for labor induction was also reduced. In a study , a group of researchers collected data from a university hospital. Over women presented at the hospital with signs of labor, like bloody show or ruptured membranes, and they were asked about their sexual activity in the week prior.

They concluded that sexual intercourse may very well be associated with bringing on labor. On the flip side, a article published in Obstetrics and Gynecology did not show a positive relationship between sexual intercourse and labor. In the study, around women were split into two groups and given instructions to either have sex in the weeks before delivery or to abstain.

The rate of spontaneous labor between the two groups was Pretty much the same. Further, an earlier study that appeared in the same publication echoed these results. This time, the researchers examined 47 women who had sex at term 39 weeks versus another 46 who were not sexually active. The gestational age of the babies born to the sexually active women was actually slightly older The team concluded that sex at term does not induce labor or ripen the cervix.

Related: How to start labor contractions. In other words, sex may or may not induce labor. But is sex safe during pregnancy?