Perhaps the most unsettling way birth control tinkers with love lives is that it may steer women toward genetically unsuitable mates. By successfully tricking the body into thinking its pregnant, underlying sexual behaviors follow suit, diverting single women toward more genetically similar men [source: LiveScience]. Why is that potentially troublesome? Although humans tend to practice assortative mating, in which people with similar backgrounds and sociodemographics couple up; genetically, however, opposites attract.
A 2008 study published in the Proceedings of the Royal Society B found that women taking hormonal contraception found men more attractive who had similar major histocompatibility complex (MHC) genes. For naturally cycling women, however, the opposite is true. That's because more dissimilar MHC genes produce hardier immune systems in their offspring [source: Wenner].
That birth control MHC mix-up likely relates back to the body's fake pregnancy. Carrying a child compels women to build a social support system among family and friends rather than seeking out a sexual suitor. Down the road, MHC similarity might spell trouble for a relationship, according to a separate study published in Psychological Science. In it, women in MHC-alike pairs were less sexually satisfied and more likely to cheat [source: Wenner]. The research didn't divulge women's birth control habits, but ditching the pill could reignite that muffled MHC sense and sidetrack their sexual attention away from their genetically familiar partners.
Doctors aren't putting a halt on prescriptions for the pill, however, and for a lot of women, it might still be their best option for preventing unwanted pregnancy. After all, every medication has its benefits and drawbacks. Until scientific data conclusively proves otherwise, birth control is perfectly safe and good for women's love lives -- and possibly their vocal cords and shopping habits as well.