It's unlikely that sex is is going to cause you to go into labor. But many doctors tell their pregnant patients to go ahead anyway when they are past their due date. It's worth trying. Pregnant women are often told that sex can induce labor. Compare that method with jumping up and down, running around the block or drinking castor oil and it's no surprise that surveys of pregnant women have found sex to be the most popular option.
But does that method work? According to a study of 93 pregnant women published in 2006 in the journal Obstetrics and Gynecology, those who reported having sex in their final weeks of pregnancy — about half — delivered on average at 39.9 weeks, compared with 39.3 weeks among those who had abstained.
So the bottom line is that sex during the late stages of pregnancy does not hasten delivery.