The Happy Trail

Hormonal birth control may affect attraction

It’s quite well-known that female hormonal birth control, particularly oral contraceptives, can often have some undesirable side effects. Mood swings, weight gain, tacky discharge and decreased (or more rarely, increased) libido are all commonly cited concerns.

Fortunately, with so many brands of birth control available, many women are able to fine tune their baby-blocking hormonal cocktail to minimize these side effects. Others are content to tolerate them in favor of eliminating risk or simply enjoying more spontaneous, intimate sex without need for a condom. For many women, hormonal birth control can significantly ease the pain and duration of periods; that is, if they choose to continue having periods.

It seems promising that women using oral contraceptives can simply nail down their preferences with experimentation. But in one crucial way, they may lose all sense of preference completely.

It turns out that the extent of birth control side effects doesn’t necessarily end with physiology.

According to some studies, romantic, platonic and sexual attraction may all be significantly affected by the use of hormonal birth control—flipped, in fact—at the level of DNA itself.

In studies where individuals rate the dank, well-used t-shirts of members the opposite sex, both women and men were significantly more attracted to the scents of individuals who have complementary (dissimilar) genes to their own at the locus coding for the major histocompability complex (MHC).

MHC is a regulator of immune system functioning: its molecules mediate interactions between white blood cells, and determine both organ transplant compatibility and susceptibility to autoimmune disease. Crucially, MHC also largely influences body odor.

But what’s crazier is that women who were on hormonal birth control did not have this effect—there was no significant difference in how attractive they found similar versus dissimilar eau d’MHC.

It makes sense when you think about it: if you could smell out a mate with a complementary immune system to yours, resulting in super-immune offspring, well, that would be pretty damn adaptive. Evolutionary theory checks out.

But when pregnant, and not searching for a mate, what does it matter? It may actually be more beneficial to surround yourself with similar-gened kin who are more likely to care for you, rather than expend energy chasing flighty, fit studs.

Hormonal birth control prevents ovulation by basically tricking the body to think it’s pregnant. Studies have found that women who were on birth control when they met their partner are significantly more likely to leave them after going off birth control to conceive. It doesn’t work like that in reverse, however; women are typically still attracted to partners they met while off the pill even if they start taking it or become pregnant.

Taking hormonal contraceptives doesn’t change one’s genes, and it’s likely that men still tend to find the scents of women with complementary MHC genes highly attractive regardless (tragic, no?). However, studies have shown that men find women more attractive when they’re ovulating, and ovulating women more attractive in general. Women, too, are significantly hornier when they’re ovulating (it’s kind of scary the tricks your body has up its sleeve to make y’all make that baby).

Because hormonal contraceptives prevent ovulation, this facet of attraction is affected as well. It’s important to have chemistry at all stages of the monthly cycle, but hormonal birth control grinds that wheel to a halt, blurring the senses.

This all sounds pretty scary, but it doesn’t have to be (not trying to break anybody up!). While there’s no perfect solution yet, there are non-hormonal alternatives, such as the copper IUD, which is just as effective as the pill and lasts for 10 years! Another strategy that I currently employ is to go off the pill when single, then back on it when it’s convenient for a relationship. You could also just continue, y’know, not actually caring about the immune system of your potential young in your casual college relationships.

Regardless, MHC isn’t an absolute indicator of compatibility; attraction and mate choice is incredibly multifaceted, and human olfactory senses may be too under-prioritized to be considered so crucial to sexual attraction. Maybe if the women had seen the men inside those t-shirts, for example, they would have made different calls on who they wanted to take home.

But for some people, the decisions made while under the influence of pretend-pregnancy can have life-altering consequences. It’s probably healthy to at least take a break from the stuff every now again to check your head and to partake in experiencing the full scope of lust and sexuality, even if staying safe means you can’t necessarily experience all of it at once!