The amount of estrogen in different birth control pills can affect the way women perceive other women, according to a study of 42 women taking hormonal birth control. Okay. Cool.
As LiveScience reports, the small sample included women on some form of contraception that included both estrogen and progesterone, including different brands of birth control pills and vaginal rings (like NuvaRing). Most took pills, but the group was fairly evenly divided in terms of the quantity of hormones in their choice of birth control: half of the women took ultra-low doses of hormones (between 0.015 mg and 0.020 mg of estrogen) while the other half took low-dose hormones (containing 0.030 mg to 0.035 mg of estrogen). For the study, all participants were asked to review images of men and women and then rate them in terms of their attractiveness, sex appeal, health and seeming energy level; the women then ranked each characteristic in terms of its importance.
Researchers found that the higher the dose of estrogen in a woman's birth control, the more likely she became to pay close attention to potential female competitors, and to start exhibiting what's known as "mate-guarding" behavior. This might sound like hormonal birth control is turning women into jealous fellow-woman-haters, but that's not actually what the results mean. Here's LiveScience on why no one should jump to any conclusions:
Without measuring the women's hormone levels in the blood, the researchers could not pinpoint exactly how the hormones may have affected the participants' rankings of other women, [Valentina Piccoli, one of the study's researchers] said. "This mechanism may be a direct result of the hormones ingested via contraceptive pill use," or it could result from changes in the body's natural hormone levels that occur in women using the contraceptive, Piccoli told Live Science.
She noted the findings are preliminary and should be treated with caution. The study did not have a control group in which women were taking a placebo instead of birth control pills ... Piccoli stressed that, in the new study, the researchers did not administer different doses of estrogen but only assessed the doses of the hormone that were in the contraceptives the women took. Therefore, the study does not show a cause-and-effect relationship between the different levels of estrogen and what the researchers have called "objectification" of other women, she said.
Basically, there's a whole lot more research to be done on the subject, and nothing that's been found so far indicates that birth control is causing any "unnatural" behavior in women. But, just to preemptively note that the findings are not a reason to rally against birth control (as if the world needed another one of those), a reminder: hormonal changes happen organically all the time, and women respond to them in different ways. Birth control is not the only thing that causes women's bodies to change, and even still those changes are not always negative. If the study definitively showed that higher levels of estrogen in birth control caused women to attack one another in fits of irrational jealous rage, that would be an issue. But we're unlikely to hear that, because that's not what birth control does.