Friday Weird Science: The Baby is Due, is it Time to Get It ON?!

Jun 04 2010 Published by under Friday Weird Science

Sci, like everyone else around here, isn't immune to the sands of time. She's getting older, along with all of her friends, who are pairing up and settling down. This means two things:
1) Sci has been a bridesmaid SIX TIMES and counting so far. The tales she could tell...
2) Sci friends are having BABIES. LOTS AND LOTS OF BABIES. 400 BABIES!

(Sci is often accused of have GRATUITOUS AMOUNTS OF ENERGY. Also, she has to wonder if these guys had ever tried the energy gel called "Chocolate Outrage". It may or may not be my favorite)
And of course with all these babies comes lots of information about babies and pregnancy. Sci has now learned about conception timing, morning sickness, the things being pregnant does to your bladder, the things having babies does to your sleep, the many amazing colors babies can produce substances in, etc, etc. And she heard one "fact" that made her ears perk up. It was this one:

Having sex and achieving orgasm when you're due can help induce labor.

And her first thought was...well...can it? Tan et al. "Coitus and orgasm at term: effect on spontaneous labour and pregnancy outcome" Singapore Medical Journal, 2009.

I mean, from the outset, it might seem to make some kind of sense. Birth involves movement of the vaginal walls, so maybe intentionally contracting the walls (via orgasm) would "prime" them somehow. Or maybe the penis shoving against the cervix would cause it to dilate a little. Uterine activity happens during sex, maybe that starts moving things along. Breast stimulation can stimulate labor, so maybe foreplay does it. Frequency of sexy time (though not right at term) is correlated with expedited onset of labor. Or maybe it just makes the woman relax. Or something. On the other hand, previous studies (from this group) took women at term and told them to have more sex. They did. Labor wasn't affected.
And if sex at term affected natural labor induction, this could be a good thing. Artificial induction of labor often results in longer and more difficult labor and more C-sections. So it might be best to get the natural labor going in more cases.
So does it or doesn't it?
So for this study, the authors surveyed a whole bunch of women who were at term (over 200 total), and scheduled for a non-urgent labor induction. These women were at term, but the baby wasn't here yet, and so they would be scheduled for induction in the next week. They then had them keep "coital and orgasm diaries". They were to record how often they had sex and whether they had orgasms (there were controls for age, state of pregnancy, and number of previous children). The women were divided into groups that were or were not having sex at the point of study recruitment. They were then placed in two groups, a group that was advised to have sex, and a group that wasn't.
And then everyone had babies, by either labor induction or natural induction, and they checked out the data.
And the results are in a GIANT TABLE. Ick. And it's one that Sci cannot graph for you. She's a little upset about this. But she'll recover.

Anyway, there was a significant increase in the amount of sex had by the group that was being advised to have sex. They went forth and f***ed as advised. And there was a significant result for sex...but it wasn't the one you'd expect.
Having sex DECREASED the induction of spontaneous labor. The time from recruitment to birth was longer in women who were having sex. Similar for women who reported orgasm. Keep in mind though, it wasn't significant. It was p=0.052, which technically counts as a trend. Women who had sex did have babies with a higher Apgar score in the first five minutes (a healthier appearance at birth), but this doesn't really signify, as all babies that were born were healthy.
So what does this mean? Well, it may mean nothing. One study found that sex increased the odds of labor (Tan, 2006). Another study (Schiffir, 2006) found no effect. This one finds that sex decreases the odds of labor. Put it all together and it looks like one big pile of nothin'.
So the question now is where to go from here. The authors did note that their women only had a week. Maybe sex in the last trimester helps. Maybe two weeks? Maybe more frequently? Maybe just at the right time? Who knows, really. This is all self report stuff, so maybe keeping an eye on them while they did it might help.
And for all you who chime in in the comments stating "WELL IT WORKED FOR ME AND U SUCK", let's all pause. Anecdotes aren't data. And for 43 of the women who orgasmed, and 49 of the women who had sex, it worked for them, too. So you might just be lucky. And there's nothing wrong with gettin' lucky, amirite?
Tan PC, Yow CM, & Omar SZ (2009). Coitus and orgasm at term: effect on spontaneous labour and pregnancy outcome. Singapore medical journal, 50 (11), 1062-7 PMID: 19960160

14 responses so far

  • The best induction-of-labor anecdote in need of systematic study that I heard while gravid: consumption of a chocolate cheesecake.
    Were I planning further reproduction, that's an experimental group of which I would gladly be a part.


  • hectocotyli says:

    I'm have rather NSFTV fantasies for an episode of Mythbusters...
    Another one of the purported birth-quickening benefits of sex is prostaglandins in semen. Said to soften the cervix. There's gotta be some pubmed-sourced explorations of that, no?

  • canuck_grad says:

    Just chiming in to say the same thing as hectocotyli... I heard it was the sperm as well - that whatever is in the gel they often use to induce labour is similar to what is naturally in sperm. Did they track partner orgasms (although I somehow doubt there were many men not climaxing lol)? But more importantly, whether or not they wore a condom (or even pulled out?) - some men are kind of freaked out by the thought of their sperm going in there with the baby.
    Another thought...let's say that there are some women who will just need to be induced regardless (without induction they would go a long long time overdue). But that sex (or orgasm or sperm or whatever) promotes labour among those women who would go into labour naturally in a reasonable amount of time. So it might be interesting to look at just those women who weren't induced, and see if sex/orgasm/sperm reduced time until labour for those women.

  • Scicurious says:

    hectocotyli and canuck_grad: yes, one of the studies cited was the effect of Prostaglandin E, which is contained in semen, but they didn't control for that.
    As far as induction, all of these women were overdue by at least a week already, and that's why they were scheduled for induction. So I think their thinking was that if anyone was going to go into labor, it would be them. But they could also conduct a study of women in the last trimester, none of whom were scheduled, and check it that way. But in all of these women (some of whom were not induced, just scheduled for induction, half of them gave birth naturally prior to the induction date) sex tended to reduce the odds of inducing naturally in women who were due (though it still wasn't quite significant.)

  • C says:

    People told me the same thing, and the explanation was the chemicals involved - the prostaglandins in semen, plus oxytocin (your favorite!) if the woman orgasms. We tried it, but only concluded that it is SUPER AWKWARD to have sex when nine months pregnant.
    I second Dr. Free-Ride...I'd like to see more research done into that chocolate cheesecake method 🙂

  • Sxydocma1 says:

    Dear Sci - Great post. I'm disappointed in this data. But, as my thesis advisor always said, the data is the data. My daughter was born the following morning after my husband and I had sex (albeit the worst sex ever, and we've blocked it from our memories), and I always like to think that was the reason she was born exactly on her due date. Because I wasn't going to be pregnant for another second after her due date - no way.

  • theshortearedowl says:

    Surely the theory is that orgasm releases oxytocin, which is used to induce labour? I'm interested that it didn't work. Are we sure none of the orgasmers were faking?

  • Blark says:

    What's the point in doing a study of this kind and not explicitly stating whether or not condoms were used by the individuals? I mean, I'm all for "they probably didn't because what's the point in using one once you're pregnant" but that's making a lot of assumptions....

  • Kathryn says:

    Oxytocin induction is not always successful. Prostaglandins, fibrinogen and cortisol, among others, also have influence, and as far as I can find in a limited search, no one thing has been isolated as the absolute instigator of labor. As an aside, I can't imagine much that would be less appealing than my beached whale self at term (5'2" with a 9lb. baby), not to mention the contortions required to accomplish love-making.

  • KitKat says:

    It would also be interesting to factor in whether there was any dilation of the subjects prior to intercourse...or contractions, albeit infrequent. I think there may be more evidence for prostaglandins etc. working (speeding up the process) once labor has already started, but I'm too lazy to look into the references right now. My personal experience: when dilated to 1cm, and with infrequent contractions (every 10-20 minutes), my partner and I decided to try to speed things worked, as within a half hour of intercourse (SANS CONDOMS), contractions were every two minutes apart. We headed to the hospital, and I delivered my firstborn four hours later.

  • FiSH says:

    There are a lot of traditions (read superstitions)in different countries and cultures regarding hastening the onset of labor. This is the perfect situation for the development of superstitions (which is why annecdotal evidence is so worthless as Sci pointed out more politely) - once a woman reaches term virtually anything she does might be correlated with induction of labor because it becomes more and more likely to occur. This is just where are brains don't seem to be wired to understand basic statistics. Along a similar vein, a lot of people think that they can predict the sex of the baby (my favorite was a Yorkshire tradition - you take a needle on a thread and dangle it over mom's belly, if it rotates clockwise it is a boy,if it rotates counterclockwise it is a girl) - people believe they can predict the babies sex because they are right half the time (hey, after all, if you are right half of the time that's much better than most other things in life).

  • KitKat says:

    I would have to dig up the full-text article to decently evaluate the data, but in support of the above, the following shows up in a google search of the terms cervical ripening and semen:
    "Unprotected sexual
    intercourse causes uterine contractions through the action of prostaglandins in semen"
    From: Clinical Obstetrics and Gynecology:
    June 2007 - Volume 50 - Issue 2 - pp 547-557
    doi: 10.1097/GRF.0b013e31804c9b11 Norwitz et al.
    Current Controversies in Obstetrics: What Is an Obstetrician to Do? states

  • Rachael says:

    If there was ever a myth started by a man for his own self interest, this seems to be it. As a mother with three children I can safely say that the only thing that induced me to nooky at that point was the hope of starting labor.