There are some known side effects of birth control pills and these include nausea, vomiting, cramps, bloating and even hair growth. However a new study suggests another possible side effect women might experience while taking the pill: picking up men who are not so sexually satisfying. The study was published the Oct. 12 issue of Proceedings of the Royal Society B.
The researchers surveyed 2,500 heterosexual women with one child. The researchers asked the women about their relationship with their child's biological father. About 1,000 of the women were taking the pill, while 1500 used no form of hormonal contraception.
Results showed that women who took the pill were less sexually satisfied, found their partners less attractive, and were more likely to be the one to initiate an eventual separation. However on the brighter side these same women said they were more satisfied with their men's paternal traits - like being caring and reliable - and the study found these women had relationships on average two years longer than women who weren't on the pill.
“Our results show some positive and negative consequences of using the pill when a woman meets her partner,” study author Dr. Craig Roberts, professor of psychology at the University of Stirling in Scotland, said in a written statement. “Such women may, on average, be less satisfied with the sexual aspects of their relationship, but more so with non-sexual aspects,” he said.
The reason for this phenomenon is unclear. Preferences in mates shift over the menstrual cycle, according to Roberts. When women are ovulating they might be more interested in someone they find sexually attractive, and when women aren't ovulating they are more interested in men who possess fatherly traits.
The mechanism for the finding is by no means certain, but Roberts speculated that it could have something to do with a set of genes called the major histocompatibility complex (MHC), a key component of a person's immune system. This set of genes also has an important evolutionary role in guiding people to find mates who are genetically dissimilar, because genetic diversity within their offspring's MHC will lead to an increased chance of surviving novel diseases and environments.
“Women tend to find genetically dissimilar men attractive because resulting babies will more likely be healthy,” said Roberts. “It's part of the subconscious 'chemistry' of attraction between men and women.” But women taking the pill don't experience these shifts, and that might explain why they are more likely to be attracted to the caring but less sexually satisfying men.
Women on the pill may end up finding men with MHC genes similar to theirs more attractive. This may lead to lower sexual satisfaction but will land them with more reliable men who, ultimately, make them more generally satisfied.
Roberts said that his study controlled for factors such as individual and country-specific attitudes to sex and relationships. He said that the results might be something for women to consider when deciding whether to settle down with a partner. Roberts said in the statement that perhaps women should opt for another kind of birth control. “Choosing a non-hormonal barrier method of contraception for a few months before getting married might be one way for a woman to check or reassure herself that she's still attracted to her partner,” he said.