Trying to Bring On Labor? Forget Sex and Spicy Foods. Only Nipple Stimulation Works.

My first pregnancy, I watched in eager anticipation as my due date arrived and then watched in frustration as it slid into the past. At 40 weeks, my belly seemed enormous. I felt like an overripe melon, which, in a not-so-funny coincidence, was exactly how my pregnancy app described the size of my baby.

To try to stimulate labor, my husband and I went out to eat spicy Thai food, spicy Indian food, and spicy Mexican food. All it gave me was indigestion. Then I tried walking. Lots of walking. I dragged my heavy, swollen body on long hike after long hike, completing them at a pace best described as a fast waddle. Maybe these long walks were good for me, who knows, but they failed to have the desired effect: my body refused to go into labor.

In the end, I went almost a week late–barely avoiding a medical induction–and only after having my membranes swept twice.

My second pregnancy was different. At my 39 weeks appointment, my OB predicted that I would again go a week late. “That’s just how you bake them,” she chirped at me, while giving a matter of fact state-of-the-cervix rundown: I was not dilated or effaced, and my cervix was still posterior. The only thing I was, it seemed, was deeply disappointed.

But this time around I had done research on natural methods of inducing labor. That weekend, I pulled my breastpump out of the closet, sterilized my nipple shields, plopped them on, and sat down to pump for a couple of hours while watching a movie. Coincidentally or not–I’ll never really know–I went into labor two days later and delivered punctually, on my due date. 

In retrospect, though, by inducing labor in this way, I may have unwittingly taken a bigger risk with my baby’s health than I am completely comfortable with.

In my efforts to bring on labor, I am hardly alone. According to a recent survey, 50% of pregnant women report trying at least one natural method to bring on labor. Walking is the most popular approach (43%), followed by intercourse (29%), eating spicy foods (10.5%), and nipple stimulation (7.5%). The grand irony here is that nipple stimulation, the least common approach, is the only one with solid scientific support.

Using nipple stimulation to bring on labor has a long history. Midwives in the 18th and 19th centuries used the practice to speed up stalled labors. Nipple stimulation brings on labor by releasing oxytocin, the hormone that causes contractions. Hospitals use a synthetic version of the same hormone, pitocin, to induce or augment a stalled labor.

A 2005 meta-analysis of six randomized control trials (the gold standard for medical studies) found that nipple stimulation increases the likelihood of labor. A total of 719 pregnant women at term were randomly assigned to stimulate their nipples for several hours or not. 37.8% went into labor within the 3 days following nipple stimulation, compared to 6.4% of the controls.

This difference, large in relative terms, was statistically significant. Still, two-thirds of women failed to go into labor even after nipple stimulation–underscoring that the method is no guarantee.

(Note to the do-it-yourselfers or those fearful of accidentally inducing labor: Nipple stimulation in these studies did not consist of a few random suckles, squeezes, or tugs. It was a serious, concerted effort. Women were instructed to gently stimulate one nipple for 10-15 minutes before switching to the other side, and to continue alternating between breasts for an hour, 3 times a day.)

Using nipple stimulation for inducing labor would probably be a more widely known and recommended practice were there not concerns about its safety. One of the studies in the 2005 meta-analysis, conducted with high-risk women delivering at a hospital in India, was stopped early because of 4 fetal deaths: 3 in the nipple stimulation group, and 1 in the oxytocin induction group. (None of the other 5 studies reported any deaths.) Because of this, the meta-analysis concludes:

Until safety issues have been fully evaluated it [nipple stimulation] should not be considered for use in a high-risk population”

It’s hard to know what to make of these safety concerns. The women in the Indian study were considered high risk because they had intrauterine growth retardation, high blood pressure, or were post-term. But the researchers failed to report which of these risk factors was associated with fetal death, or to provide any additional details about these deaths, other than to say one of lost fetuses did not appear to have any congenital abnormalities.

That nipple stimulation contributed to these deaths is certainly plausible. Nipple stimulation can result in uterine hyperstimulation--contractions that are too frequent or prolonged, and which can lead to fetal distress.* This is why women are told to alternate between breasts instead of stimulating both nipples simultaneously and to pause during contractions.

German study found uterine hyperstimulation occurred in 10% of women during nipple stimulation, and in 1% this was accompanied by reversible abnormalities in fetal heart rate patterns. Based on this, the authors caution against using nipple stimulation without medical supervision:

Due to the conflicting reports in the literature and because of the potential hazards involved, the use of nipple stimulation for the induction of uterine contractions can be advocated only in a controlled clinical setting. Its application without medical supervision, as propagated in the lay press, is definitely contraindicated.

In sum: nipple stimulation does increase the likelihood of going into labor. But because it can cause contractions that are too long or too intense, it is not recommended for women with high-risk pregnancies.

Below is a quick rundown on the evidence (read: lack thereof) for other natural induction methods:

Walking. Walking is the most recommended and most commonly attempted method of inducing labor. It is true that in late pregnancy, walking seems to increase the frequency and strength of Braxton Hicks contractions. There is no evidence, though, that walking speeds the onset of labor.

Eating spicy foods. There is no evidence that spicy foods cause labor.

Acupuncture. A review article of 3 randomized control trials, consisting of 212 women, found that acupuncture reduced the number of women who needed to a medical induction (33% versus 54%), but failed to find a difference in when the women went into labor. Because of the inconsistent results and methods (the type of acupuncture varied between studies), the reviewers felt no conclusions could be drawn without additional research. Since then, other randomized control trials have found no benefit of acupuncture for bringing on labor (see here, here, and here).

Having sex. As one researcher put it, intercourse would be a “safe, effective, and perhaps even fun” [italics mine] way to induce labor. Fun aside, it’s biologically plausible that sex would bring on labor. Semen contains prostaglandins, which are known to ripen the cervix. Orgasms promote the release of oxytocin and can therefore stimulate uterine contractions during late pregnancy. Foreplay involving nipple stimulation could also release oxytocin. A small observational study found that women who reported having sex after 39 weeks were much less likely to go post-term or need to be induced.

Sounds pretty good, right? Alas, the most recent, best-designed, and largest study to date, a randomized clinical trial conducted in Southeast Asia, failed to replicate these findings. Two hundred ten women were recruited from a prenatal clinic, where they had been scheduled for inductions. They were randomly assigned to be counselled by a physician to have sex or to receive standard counselling. The women kept daily diaries tracking when they had sex and whether they experienced an orgasm. Although women who were told to have sex to bring on labor were more likely to have sex before delivery (60% versus 40%), they did not differ in cervical ripeness or in their likelihood to go into labor on their own.

It’s possible that sex does bring on labor, but the Southeast Asian study was too small to provide a fair test. A sample of 210 women is not large. Making matters worse, a fair number of the controls had sex, watering down the comparison between the cases and controls.

Knowing this, in a separate analysis of the same data, the researchers compared all the women who reported having sex with the women who did not, regardless of whether they had been cases or controls. They still found no effect of intercourse. If anything, women who had sex during the study period went into labor later than women who refrained. An earlier but smaller clinical trial similarly found no benefit of sex.

In sum: sex late in pregnancy–after 39 weeks–does not appear to bring on labor. But it perhaps just might be fun.

Did you try any natural methods to induce labor? And do you think they worked?

Footnote

* The evidence on nipple stimulation and uterine hyperstimulation comes mainly from a series of studies conducted in the 1980s. These studies examined whether nipple stimulation was a viable alternative to pitocin for use in contraction stress tests. Contraction stress tests monitor fetal heart rate during contractions to ensure the fetus can safely withstand labor. The studies variously found no instances of hyperstimulation, hyperstimulation in 10% of women, and hyperstimulation in 12% of women. A final study, which also reported on fetal distress, found hyperstimulation with fetal heart rate changes in 2.9% of women using nipple stimulation, compared to 1% of women using pitocin.

 

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About Amy Kiefer

I am a research scientist and mother of two. I was born in Chicago, but for the past 10 years I have lived in the San Francisco Bay Area with my software engineer husband (a cliché, I know). I love digging into the scientific literature and summarizing research findings. In this blog, I try to present an unbiased and sane take on research topics of interest to soon-to-be and new parents.
This entry was posted in Labor, Pregnancy. Bookmark the permalink.

8 Responses to Trying to Bring On Labor? Forget Sex and Spicy Foods. Only Nipple Stimulation Works.

  1. Rhea Marie says:

    This is an interesting review of the popular at-home methods for inducing labor. I’ve always thought that eating spicy food sounded positively ridiculous for inducing. I walked (haha “walked”) a lot with my husband and also was on an elliptical at the gym 5 days a week (which caused considerably less pain and discomfort than walking because I had severe pubis symphysis dysfunction), but I wouldn’t say it was done to start labor. We had sex regularly, which is perhaps why my cervix was in a favorable condition well before my due date? Who knows. A few days after my due date my OB performed a membrane sweep (I had been 1 cm dilated for a week or two before that), which, indeed, kickstarted labor (immediately) but it lasted for 36 hours (in which I didn’t dilate beyond 3-4 cm for 24+ hours or, until they broke my water in the hospital after I had an epidural) and was followed by severe (1.7L) postpartum hemorrhage. Membrane sweeps aren’t known to have such negative effects, but I can’t help but wonder if it would have been better to wait until I went into labor “naturally”. Conversely, my baby was quite large (9 lbs 7 oz), and complications tend to increase in such cases.

    Anyway, I was surprised you didn’t mention castor oil, since it’s also quite a popular method to attempt to induce labor. I was definitely unwilling to try it, though. Shockingly, there isn’t supportive evidence that this is effective: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD003099.pub2/abstract

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  2. Rhea, thanks for sharing your story! Interestingly, I had the same experience with membrane sweeping for my first pregnancy. It worked for kickstarting labor, but my labor lasted 45 hours! I have often wondered if my body wasn’t quite ready. My son was also occiput posterior–the dread back labor–which probably also slowed things down.

    I didn’t talk about castor oil, because I did not realize women were still using it! It sounds horrible. No evidence that it works, and lots of evidence that it causes diarrhea and nausea. Just what one needs in late pregnancy!

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  5. Clara KB says:

    Hi Amy, thanks again for the great job you do with your blog.
    Now in my 8th month, I’ve just come across a study on how date fruits help start labour. Here it is : http://www.ncbi.nlm.nih.gov/pubmed/21280989
    I love dates so I’m most pleased to find a scientific reason to eat a lot of them in the next four weeks 🙂 But from a more rational perspective, what do you think of this study?

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    • Grzegorz says:

      Nice post 🙂 I found something similar to Clara finding: “The Effect of Late Pregnancy Consumption of Date Fruit on Cervical Ripening in Nulliparous Women” ( https://www.ncbi.nlm.nih.gov/pubmed/21280989 ). Here is an interesting quote from this article:
      “An ideal agent for cervical ripening should prepare the cervix for delivery with minimum complications for the mother and the fetus (8). Natural non-drug methods, including non-invasive techniques, are more effective, more economical, and safer than pharmacological methods. Current non-drug methods include castor oil, evening primrose oil, raspberry leaf, sisymbrium irio (London rocket), and date fruit (9).”

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