essay / research

Your brain on birth control

It’s as complicated as the morning after.

Here’s the thing about hormonal birth control: It changes lots of stuff in women’s bodies. Not all that stuff is necessarily good or bad — it’s just a lot. So we should be paying attention if and when we use it. Recent controversy over the birth control device NuvaRing has been reminding us why, while also prompting me to look into the ways hormonal birth control affects our moods and our brains.

Over the past few years, thousands of women have sued the pharmaceutical company Merck over concerns with blood clots potentially caused by NuvaRing — a ring that prevents pregnancy by releasing hormones into the vagina. Just last month, Merck agreed to pay $100 million to settle those lawsuits, if enough of the women involved take the deal.

NuvaRing’s safety is still in dispute. After wading through lots of reportage (see Vanity Fair and Medium for some dialogue) and literature on the issue, I’m comfortable with only this partial conclusion: If you plan to use hormonal birth control, especially NuvaRing, find out whether you’re predisposed to blood clots. And that question should be part of a broader discussion with your physician about the risks or expected effects of any hormonal contraception. Clotting, of course, is not the only bodily process affected by hormonal birth control. That point brings us to mood and the brain.

We’ve known for a long time that birth control can affect women’s moods — not particularly shocking. After all, it maintains higher levels of the hormones estrogen and progestin, which have diffuse effects in our bodies. We just don’t know many specifics of how these changes in mood come about. For one thing, effects on mood can be broken into the short- and long-term. Some women experience mood swings on birth control, which can be thought of as short-term, if potentially consistent, effects. One epidemiological study looked more at the long-term by probing the relationship between birth control use and depression. Researchers found that women using hormonal contraceptives reported fewer symptoms of depression and fewer suicide attempts, compared to women not using those contraceptives.

Since this is just one inconclusive study, the takeaway here is not that hormonal birth control decreases depression. If anything, this finding highlights the complications in figuring out how contraceptives affect mental states. As other researchers have pointed out, many other factors could be contributing to the results besides the use of birth control alone. The women who use birth control, for example, may represent a subset of the population that’s generally less vulnerable to depression. As usual, we’ll need more studies to find out.

Some studies will look not at reported moods, but at the details of the brain. Estrogen’s mood effects stem at least partly from its relationship with the neurotransmitter serotonin, which is known to regulate mood. (Although: don’t buy the common claim that depression is universally caused by low serotonin. The drug tianeptine, for example, lowers serotonin levels and sometimes actually reduces depressive symptoms in so doing.) Estrogen can influence how serotonin is made, where it goes, and how it gets broken down in the brain. So again, no wonder that a pill, shot, patch or vaginal ring that raises estrogen levels can significantly affect how women feel.

In one somewhat small study, researchers also found birth control to be associated with changes in brain structure. Compared to the non-birth control users, the women on hormonal contraceptives had more gray matter, or neuronal cell bodies, in different parts of the brain. This study didn’t test behavior or cognition, so it’s not clear what this structural difference means. Still, it looks like it’s there. Hence my overall point: we have far from perfect knowledge about the ways hormonal birth control affects our bodies.

None of this is meant to scare, especially since not all these effects of birth control are bad. And though I’ve looked at hormonal contraception as a group, it’s important to consider what’s unique about different methods. I’ve just meant to provoke questions about women’s reproductive options, looking beyond reproduction itself: out from the uterus toward the brain, you might say. It shouldn’t take a multi-million dollar lawsuit against a pharmaceutical company for women to gain information on how birth control affects our bodies. Now that more people are talking, let’s just keep it up.

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2 thoughts on “Your brain on birth control

  1. Yeah, keep the dialogue going! Thanks for pointing out specific studies dealing with a wide range of possible effects. What’s most troubling to me is that there are so few studies on this, when hormonal birth control has such widespread use in the Western world. Equally troubling, I read somewhere that Viagra has had more studies conducted on it than any hormonal birth-control, or any drug marketed specifically to women, for that matter. (Do you know how I could possibly back that statement up? Or is it false? Both good things to know.)

    In the study you cite on relationship to depression, another factor they seem to miss is that a reduction in depression/suicide attempts might also be related to not having anxiety about accidentally getting pregnant. It doesn’t even appear to be something they account for! “At ages 25-34 years, hormonal contraceptive users had lower mean levels of concurrent depressive symptoms (β = -1.04, 95% confidence interval: -1.73, -0.35) and were less likely to report a past-year suicide attempt (odds ratio = 0.37, 95% confidence interval: 0.14, 0.95) than women using low-efficacy contraception or no contraception“. I did not need science to point that out for me! A more valid comparison would have been, how would hormonal contraceptive users compare to non-hormonal, but equally effective contraceptive users? Some that come to mind are the copper IUD and condom use (which I would certainly count as not low-efficacy.)

  2. Yeah unsurprising for an observational study, there’s a lot to unpack regarding the comparisons. They grouped women using condoms, diaphragms and vaginal sponges as using “less effective” methods, and they did find higher depression rates in this group compared to the hormonal birth control users. However, they note that women in monogamous relationships were more likely to use hormonal birth control than barrier methods, suggesting relationship stability might be a factor. They tried to check against that possibility by looking at the effect of relationship stability within the “most effective” group — here defined as IUD users and women who have had tubal ligation — and found no correlation. Buuut that of course doesn’t directly determine whether hormonal contraceptive users’ greater likelihood of being in stable relationships reduces their incidences of depression. Just makes it look less likely that relationship stability robustly defends against depression.

    I remember your raising that point about Viagra studies before — crazy if that’s true. I haven’t been able to pinpoint a comparison between the number of studies done on Viagra and the number of studies done on birth control. But I wouldn’t be shocked if Viagra has had more studies conducted on it compared to any individual method of hormonal birth control (ie, to confirm that the pharmaceutical industry puts more attention toward the state of penises than toward women’s reproductive health).

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