# The surprising link between women’s brains and the birth control pill | Sarah E. Hill | TEDxVienna https://www.youtube.com/watch?v=RdwLAyWHBVs Translation: zh-CN [00:24] How much do you know about the birth [00:26] control pill? [00:28] Like, [00:29] really know about the birth control [00:32] pill? [00:33] Now, if you're a woman in the audience, [00:35] you've probably heard the drill, right? [00:37] You have an increased risk of stroke or [00:41] weight gain [00:43] or, you know, you might get a risk of [00:45] pulmonary embolism, especially if you're [00:47] over 35 and smoke. [00:50] Right, guys in the audience, you [00:51] probably know that if your partner is on [00:53] the pill, that it might spare you the [00:56] cruel and unusual fate of having to wear [00:59] a condom during sex. [01:02] Right? [01:03] But, like, how much do you know about [01:05] the birth control pill when it comes to [01:08] the part of our bodies that most of us [01:11] care about more than any other? [01:14] Right, the brain. [01:17] How much do we know about the birth [01:18] control pill in the brain? [01:21] Right, now asking this question is [01:23] something that feels a little risky to a [01:25] lot of women. [01:26] Right, and this is because to ask this [01:28] question violates two rules of feminism [01:34] that most of us adopt sort of [01:36] unconsciously [01:37] since childhood. [01:39] Right? And the first of these rules [01:42] is do not criticize the birth control [01:45] pill. [01:46] Right, women are, understandably, very [01:49] protective of the birth control pill. [01:51] Right, and the reason for this is that [01:53] it's been absolutely amazing for women. [01:56] Right, and just to illustrate this for [01:58] you, if you look at this figure behind [02:00] me, what you'll see is the proportion of [02:02] female applicants to law and medical [02:06] schools prior to the birth control pill [02:08] being made legally available to single [02:11] women. [02:12] Right, they made up just 10% of the [02:14] and women are 50% of the applicant pool. [02:16] Flash forward 20 years later [02:23] By allowing women to regulate their [02:25] fertility, [02:26] right, and be able to plan, [02:29] women made longer-term career goals, [02:31] longer-term educational goals, and the [02:34] birth control pill and all of the [02:35] freedom it afforded us is responsible [02:38] for so much of women's advancement in [02:40] terms of being able to become [02:42] financially independent from men. [02:44] Right, and so the pill has been a really [02:46] amazing force in the lives of women. [02:49] And because of this, questioning or [02:52] thinking critically about the birth [02:53] control pill can scare people, right, [02:56] making them think that we'll have to go [02:57] back to the time when women were [02:59] financially dependent on men and lose [03:01] some of our freedom. Right, despite the [03:04] fact that knowledge is always powerful, [03:07] right, and talking critically about the [03:08] birth control pill doesn't mean that we [03:10] have to give it up. [03:13] Right, the second rule that we get in [03:15] trouble with when we do want to talk [03:17] critically about the birth control pill [03:18] in the brain is the rule that tells us [03:21] we absolutely cannot talk about sex [03:24] hormone involvement in the brain if [03:26] you're a woman. [03:27] Right, and the reason for this is that [03:29] for a very long time, women were treated [03:32] as overly emotional, less rational [03:35] versions of men because of our changing [03:38] sex hormones. [03:40] Right, there was a lot of sexist [03:41] rhetoric that said that women shouldn't [03:43] possibly be able to hold important jobs, [03:46] right, own land or vote because our [03:49] cyclically changing hormones just made [03:51] us completely irrational, right, and [03:54] therefore not you know, not somebody who [03:56] should be in these types of positions. [03:59] Right, but this idea prevents us from [04:01] being able to have thoughtful [04:02] discussions about the pill, and they're [04:05] also totally not backed up in science. [04:08] Right, to start with, women's hormones [04:11] change cyclically, but they're not [04:13] unpredictable. They're not capricious or [04:16] whimsical or fickle. [04:19] If you tell me a woman's age [04:22] and you tell me the first day of her [04:24] last menstrual cycle, I'll be able to [04:26] predict with an almost alarming amount [04:28] of precision exactly what her sex [04:31] hormones are doing at that moment. [04:33] Right, if she's in the first half of her [04:35] cycle, we'll find that the sex hormone [04:37] estrogen is relatively high relative to [04:40] levels of progesterone. [04:42] And if it's the second half of the [04:43] cycle, I can predict that progesterone [04:46] levels are going to be relatively high [04:48] relative to levels of estrogen. [04:51] Right, so even though women's hormones [04:53] change cyclically, they're not [04:55] unpredictable and capricious. [04:58] Men's primary sex hormone, testosterone, [05:01] on the other hand, is a totally [05:03] different story. [05:05] Right, so we know from research that [05:07] men's levels of testosterone change in [05:10] response to age, time of day, whether or [05:13] not he has children, whether or not he's [05:15] just watched sports, um whether or not [05:17] he's passed weapons. Like, if you see a [05:19] gun, that changes testosterone levels, [05:21] the presence of attractive women, and a [05:23] whole bunch of other stuff, too. [05:26] Okay, so if anybody's got capricious [05:28] hormones, [05:29] it's men. [05:30] Right? [05:33] So, [05:38] So, the idea The idea that our sex [05:41] hormones influence our brain shouldn't [05:43] be problematic, right? Women's hormones [05:45] change and they influence women's [05:47] behavior and how women think, feel, and [05:49] what they do. Men's hormones change, and [05:51] when they change, they also influence [05:53] what men think, feel, and do. Right, and [05:55] we have to start having conversations [05:57] about these things because not doing so [06:00] is bad for women's health. [06:02] Right, because we need to break these [06:04] rules that have prevented us from having [06:06] thoughtful conversations about the birth [06:08] control pill and who it makes women. [06:11] Right, because even though women take [06:13] the birth control pill for a small [06:14] number of targeted effects, right, it [06:17] has an impact on women's bodies from [06:19] head to toe, including the brain. [06:22] Right, and the way that the birth [06:23] control pill works is it changes women's [06:25] levels of sex hormones. And even though [06:28] we tend to think of our sex hormones as [06:30] something that happens to us, right, [06:32] like something that causes puberty and [06:34] hair growth in places that we don't [06:36] really want to talk about in polite [06:37] company, our sex hormones are actually a [06:39] key part of the signaling machinery that [06:42] our brain uses to create the experience [06:44] of being the person that we are. And so [06:47] when we change women's sex hormones, [06:49] we're actually changing the version of [06:51] their brain that they are creating. [06:54] Right, and there's a growing body of [06:55] research in psychology and neuroscience [06:58] that shows this to be true. [07:00] Right, for example, just thinking about [07:02] sexual functioning, right, which is [07:04] something that we all think about a lot, [07:06] right, we know from research that women [07:09] who are on the birth control pill [07:11] exhibit decreased sexual desire and [07:13] decreased sexual functioning relative to [07:16] their naturally cycling counterparts. [07:19] And the reason for this has everything [07:20] to do with the hormonal profile that's [07:22] created by the birth control pill. [07:25] The hormones that facilitate the sexual [07:27] response in women and facilitate sexual [07:29] desire are relatively high levels of [07:32] estrogen and testosterone and lower [07:34] levels of progesterone. Right, [07:36] progesterone actually inhibits women's [07:38] sexual desire. [07:40] And the sex hormone profile on the birth [07:41] control pill is essentially sexual [07:44] antivenom, right? It's high levels of [07:47] progesterone, a sexual inhibitor, right, [07:50] and relatively low levels of estrogen [07:52] and testosterone. And indeed, there's a [07:54] lot of research indicating that women [07:56] tend to have diminished libido um on the [07:59] response to the birth control pill. [08:01] But, it's not just sexual desire, right, [08:04] and women's desire for sex and their [08:05] sexual responsiveness that changes in [08:09] Right, it can also influence who women [08:11] are attracted to. [08:13] Right, and this is also something that's [08:15] influenced by the levels of sex hormones [08:17] that are created by the birth control [08:19] pill. [08:20] Right, so we know now from decades of [08:22] research that women's own levels of [08:24] estrogen predict the amount of [08:26] testosterone that they prefer in their [08:28] partners. In other words, the sex [08:31] hormone estrogen increases women's [08:33] attunement to cues that have [08:35] historically been linked to testosterone [08:38] levels in men. This graph that you're [08:40] looking at here is showing how women's [08:42] own levels of estrogen predict [08:44] testosterone preference. And what you [08:46] can see from this is that estrogen loves [08:49] testosterone. Right, so women, when they [08:52] have relatively high levels of estrogen, [08:54] are really keyed into facial cues that [08:56] are associated with masculinity, and [08:59] this changes their preferences um over [09:01] the course of the cycle. [09:03] Now, given that the birth control pill [09:05] keeps levels of estrogen very low, [09:08] um we can make the prediction that women [09:10] who are on the birth control pill should [09:12] prefer as partners men um who have fewer [09:16] cues associated with testosterone [09:18] preference. [09:19] Right, and that's exactly what we find. [09:22] Um so, research finds now that women who [09:24] are on the birth control pill prefer [09:26] partners with less masculine faces than [09:29] do their naturally cycling peers. And [09:32] this is something that is found both [09:34] when women are identifying men that they [09:36] would like to have as short-term sexual [09:37] partners and also the people that they'd [09:40] like to have as long-term romantic [09:42] partners. [09:43] Right, the research has also found that [09:46] pill-taking women are actually choosing [09:48] as partners men with less masculine [09:51] faces relative to naturally cycling [09:54] women. So, they've done studies where [09:56] they've brought in the partners of women [09:58] who chose their partner, whether they [09:59] were on or off of the birth control [10:01] pill, took photographs of their faces, [10:04] created facial composites, and they were [10:06] able to actually look at the the [10:08] proportion of testosterone markers on [10:11] the faces of men. And they found out [10:14] that the pill-taking women, indeed, were [10:16] choosing as partners men with fewer [10:19] testosterone markers in their faces. [10:21] Right, so the birth control pill might [10:23] be changing the face of mate [10:25] preferences. [10:27] And it's not just sex and sex-related [10:30] things. Right, sex and mating, it all [10:32] makes sense that all of that should [10:33] change in response to the birth control [10:35] pill when we really think about the idea [10:37] that it's changing women's sex hormones. [10:39] But that's just scratching the surface. [10:42] Right, because our sex hormones also [10:44] influence the other hormones in our [10:45] body, including those that are [10:48] associated with our stress response. [10:51] So, stress is something we all know. [10:53] Right, you all you know stress, sitting [10:55] in traffic, [10:57] giving a TED Talk in front of a thousand [10:59] people. Right, being on the business end [11:02] of a wildebeest stampede. Right, daily [11:04] things that happen to us. [11:07] Whenever we're the wildebeest always a [11:08] wildebeest stampede. Right? [11:12] Anytime that we're encountering a [11:13] stressor, no matter what it is, whether [11:15] it's a TED Talk or the wildebeest, [11:17] generally within about 5 minutes our [11:20] body releases the stress hormone [11:21] cortisol. Right, which tends to get kind [11:24] of a bad rap because everybody [11:26] associates it with stress, but cortisol [11:28] isn't what causes stress. Life is what [11:31] causes stress. Right, cortisol is [11:33] actually part of the way that our body [11:35] helps cope with stress. It dumps fat and [11:38] sugar into our bloodstream so we can [11:40] make a fast getaway, and it primes our [11:42] brain for learning and memory. So, that [11:44] way if we encounter a similar situation [11:46] in the future, we'll be better able to [11:49] cope with it. Right, because of this, [11:51] when we're feeling stressed out, our [11:52] body releases cortisol. [11:55] Unless you're on the birth control pill. [11:58] So, there's several decades of research [12:00] now that shows that women who are on the [12:02] birth control pill exhibit a blunted or [12:05] altogether absent cortisol response to [12:07] stress. Right, and this is something [12:09] that's potentially really important. Um [12:12] not only because this is the type of [12:14] profile that we tend to see in people [12:16] who've undergone trauma or have PTSD, [12:19] but also because it can cause structural [12:21] changes in the brain, decrease people's [12:24] ability to cope with stress, cause [12:26] problems with emotional regulation, and [12:29] impair learning and memory. [12:31] And there's some research now coming out [12:33] about the birth control pill in each one [12:35] of these processes that suggests that we [12:37] might be seeing just these patterns in [12:40] women who are on the birth control pill. [12:42] Right, and it's not just individual [12:44] women who are changed by the birth [12:47] Right, each woman lives in an [12:50] interdependent web that includes her [12:53] friends, her family members, her [12:56] romantic partners, and her colleagues. [12:58] And so, when we change what women's sex [13:00] hormones are doing, those changes are [13:03] going to echo throughout the woman's [13:05] body in ways that have a lot of effects [13:07] on her system, but they're also going to [13:09] echo throughout the world as women are [13:11] interacting with other people and [13:13] changing the face of the world. [13:16] So, it's time to throw out the old [13:18] rules. Right, and we need to start [13:20] having more, not fewer, conversations [13:23] about women's brains and the birth [13:25] the birth control pill. Right, it's [13:27] And this doesn't mean that we abandon [13:30] still going to be the best choice for a [13:32] lot of women at certain points in their [13:34] lives. It was my choice for over a [13:36] decade. Right, but it's time to put the [13:39] power of information in the hands of [13:41] women, to let them know what tradeoffs [13:43] they're making with the birth control [13:44] pill, so that way they can make informed [13:46] choices about their health and who they [13:49] most want to be. [13:51] Thank you.