Can Sex Induce Labor?

There are a lot of myths out there about ways to trigger labor—including eating spicy foods, dancing, taking a shot of castor oil, and others. The point is that by the time a person is 40 weeks pregnant, they're ready to do anything to induce labor.

Nearly 30% of 2,400 people surveyed by the maternity care organization Childbirth Connection reported trying to induce labor on their own.

But one of the most persistent myths is whether having sex can induce labor. After all, it's what got you into the situation, so can it help you out of it?

Here's what you need to know about whether sex can induce labor—including if some positions are better than others to kickstart childbirth.

What Studies Show About Sex-Induced Labor

As it turns out, sex isn't an official method that induces labor. 

"There have been many studies on sex-inducing labor. And most studies have not been able to find that the role of sexual intercourse can be used as a method of induction of labor," explained Jessica Shepherd, MD, OB-GYN, and director of minimally invasive gynecology at the University of Illinois College of Medicine in Chicago.

According to a study published in 2022 in American Family Physician, although exercise and nipple stimulation can increase the likelihood of spontaneous labor, sexual intercourse may not be effective.

And a meta-analysis published in 2019 in The Journal of Sexual Medicine looked at clinical trials involving 1,483 people. The authors write that sexual intercourse during pregnancy is commonly believed to trigger the onset of contractions and labor. 

However, in low-risk pregnancies, there is neither association with preterm birth, premature rupture of membranes, or low birth weight nor the spontaneous onset of labor at term.

The Mechanics of Pregnancy Sex

That said, it's not a fictitious idea. There are a couple of theories about why sex could prime the body for labor. 

For starters, there's the fact that sex causes mechanical irritation of the cervix, said Felice Gersh, MD, OB-GYN, and director of the Integrative Medical Group of Irvine in California.

"During sex, the physical rubbing and touching of the cervix by the penis can potentially affect the cervical mucous and stimulate the release of labor-stimulating substances in people with a history of early labor or a weak cervix," said Dr. Gersh.

Sex also involves two hormones crucial to labor: Prostaglandins and oxytocin. 

"Human semen is the biological source that is presumed to contain the highest prostaglandin concentration," said Dr. Shepherd. 

And unprotected sex is going to introduce that to the cervix. Prostaglandins soften and open the cervix, which could lead to the onset of contractions, according to the 2022 American Family Physician study.

"Meanwhile, orgasms trigger a surge of oxytocin release, which is key to the production of labor contractions," added Dr. Gersh.

"Studies have found that your body releases oxytocin upon orgasm, a hormone similar to Pitocin—the drug healthcare providers use to start or speed up labor because it causes uterine contractions," said Nita Landry, MD, OB-GYN, and co-host of the talk show "The Doctors." 

If you have post-climax contractions, you could trick your body into thinking it's time for labor contractions. However, as of November 2022, research hasn't yet proven that to be true.

Does Sex Position Matter?

A quick Google search will show a lot of debate around the best sex positions to induce labor, but that's a moot point. 

Hormonal changes bring on labor, so your sex position doesn't really matter. What matters, in theory, is that you achieve an orgasm. Still, sex-inducing labor is hypothetical, so don't worry about having sex before your due date. An orgasm isn't going to send you into labor too early spontaneously. 

A Quick Review

For people with normal, complication-free pregnancies, sex is only likely to trigger labor if they're full-term or past-term. So, give it a try if you are at that point and can't take another day.

Talk to your healthcare provider if you have concerns or have had any issues with your pregnancy. Unless they tell you otherwise, sex is safe throughout your pregnancy. However, sex is unsafe after water breaks and can lead to infections.