A reader wrote me asking about the recent post entitled “What Do Sweaty T-Shirts And The Pill Have To Do With High Divorce Rates?”
What specific hormones within birth control pills cause this change in attraction? Different birth control pills carry different hormones in varying levels…. are you better off with certain types (progesterone heavy vs. estrogen heavy) in this regard? This question arose for me after you mentioned IUDs. I’m looking to see if the mirena* (which I’ve got) has the same effect, though in general, it would be good to differentiate specific pills/methods rather than just generalize it as “The Pill”.
This is a really good question and a significant hole in the study. From what I’m aware, there are two types of hormonal birth control: ones with a combination of estrogen and progesteron (or one of it’s synthesized forms called progestins) or progestin only birth control. None of the literature I could find mentioned what specific kind of birth control was being used by the women in the studies. It was always either referred to as ‘the Pill’ or hormonal birth control. This would lead me to believe that the women were asked in a pre-study questionnaire something to the effect of “are you on hormonal birth control?” or even “are you on the Pill?” I would posit that it is progestin that is the likely culprit as one can get ‘the Pill’ in which there is no estrogen present. It is likely that some of the women who answered ‘Yes’ to the aforementioned questions were on just such a form of birth control.
Unfortunately I was unable to findany articles or papers that could give me a definitive answer, but if it is progestin that is causing women to be more attracted to the smells of men with similar major histocompatibility complexes to their own it would stand to reason that the Mirena IUD is no different.
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