Wednesday, July 15, 2009

What does this anthropologist think about hormonal birth control? Part I

ResearchBlogging.orgParts I, II, III, IV and V.

I have been working on this post on and off for the last several weeks. It has become so long that I have decided to break it up into several parts. Today is Part I.

First, I am not a medical professional. I am a PhD, not an MD, so this is not medical advice. And in fact, I am quite sure there are anthropologists out there who do not share my opinion, so this is not even anthropological advice. This is just one person’s perspective on a medication so pervasive few people even think of it as the serious prescription that it is.

Hormonal birth control has been around for many decades, and has seen many improvements, reductions in dosage, and different ways of accessing the medication, from a shot, to a patch, a ring or a pill. Hormonal birth control is used off-label for mood stabilization and acne, and increasingly these contraceptives are also approved for these non-contraceptive purposes. You’ve probably seen the ads of skinny-armed women punching at “irritability” and “bloating” in bubble letters before them with a girly rendition of “We’re not gonna take it” in the background. You’ve seen the slightly more “empowered” ads that have cropped up recently regarding the hormonal contraception that you can take continuously to avoid your period, where far stronger women are staring right into the camera and daring you to doubt their decisions.

With my feminist mindset, these ads are pretty much enough to make me think that these drugs are harmful to women, because they are 1) focusing on the non-birth control aspects of the drug in order to increase the number of consumers and 2) trying to frame the debate about contraception with a watery version of "choice" feminism. However, and this is a big however, how one feels about a commercial is not a good enough reason to dismiss a medication used by, I am guessing, a majority of reproductively aged women in this country. I was recently annoyed by a Tylenol ad, but you better believe I gave my daughter acetaminophen last week when she had a temperature of 104. I am able to get off my high horse, folks, and I’d like to do that today to discuss some recent evidence around hormonal contraception that suggests it is not the cure-all we want it to be.


Let’s just get these out of the way first. If you read the packaging and/or you have a doctor worth his/her salt, you know if you have high blood pressure, a history of blood clots or liver dysfunction, you should not take hormonal contraception. End of story, and don’t try to get around it.

But do you know that if your BMI is over 25 you are at an increased risk of unintended pregnancies? The dosage for hormonal contraception was designed for average to low-average weight women from developed countries. Brunner Huber and Hogue (2005) found that contracepting overweight and obese women had twice the odds of an unintended pregnancy compared to normal weight women. Burkman et al (2009) recently found similar results, but the relationship was not quite statistically significant. The results do seem to vary somewhat with which contraceptive is being tested. But with the average American woman’s BMI at 28, it seems as though today’s oral contraceptives may not be effective for a majority of our country’s population.*see below for additional info

Tomorrow, I’ll discuss what it means to have a “normal” menstrual cycle, and how this relates to the prevalence of hormonal contraceptives.


Brunner Huber LR, & Hogue CJ (2005). The association between body weight, unintended pregnancy resulting in a livebirth, and contraception at the time of conception Maternal and Child Health Journal, 9 (4), 413-420

Burkman RT, Fisher AC, Wan GJ, Barnowski CE, & LaGuardia KD (2009). Association between efficacy and body weight or body mass index for two low-dose oral contraceptives Contraception, 79 (6), 424-427

*Edited to add: I want to add a little more information here. Brunner Huber and Hogue surveyed women AFTER they had given birth and asked if the pregnancy was intended/unintended, and whether the individuals had used contraception or not. Among contracepting women, the number of overweight and obese women with unintended pregnancies was much higher than those with intended pregnancies. Further, they cite a pretty decent amount of literature and provide a credible mechanism for why overweight women tend to have reduced efficacy on hormonal contraceptives. I thought I would mention this because, for the sake of brevity I did not review a broad swath of the literature, but only mention two representative articles.


  1. Thanks for this eye-opening series of posts! I had never heard about the connection between BMI and contraceptive failure. A little bit scary considering the weight I've gained since starting graduate school... I look forward to reading the rest of your commentary on this subject.

  2. You're very welcome, Laura. The evidence is growing in terms of the BMI/contraceptive failure issue, though there's still a ways to go, so I hope I haven't overstated the results. Either way, I personally wouldn't use the pill (as my sole method of contraception) if my BMI were 25 or over just to be safe.