Pill may lead women to the wrong guy

01:43, Jan 31 2009

While millions of people have plenty to thank the contraceptive pill for, it turns out its contribution to the survival of the fittest, and to our relationships, might not be so complementary.

A study by British scientists suggests the pill could be responsible for skewing the hormones of women that use it, and attracting them to the "wrong" partner.

The study also suggests that taking the pill saw women's attraction shifting to men with genetically similar odours, which could affect their choice of mate.

Humans are attracted to the body odour of prospective partners, traditionally, those who are genetically dissimilar as a means of maintaining genetic diversity.

A women's sense of smell is also said to be an innate guard against inbreeding.

Genetically similar partners have more trouble conceiving and carry a higher risk of miscarriage. The researchers asked 100 study subjects to indicate which of six male body odour samples they preferred both before and after starting to use the birth control pill.


The researchers found the women's preferences changed after they began taking the pill to favour men with similar odours to their own.

The research showed the pill could even contribute to the end of relationships, as women who stop or start taking the pill may no longer find their boyfriend or husband so attractive.

Genes in the Major Histocompatibility Complex (MHC) help develop a person's distinct body odour by how they interact with skin bacteria.

While it is unclear whether body odour overpowers such traditional desirable marriage traits as looking like Brad Pitt and having Bill Gates' bank account, the study suggests its effect is considerable.

Study leader Craig Roberts said the results "showed that not only could MHC-similarity in couples lead to fertility problems, but it could ultimately lead to the breakdown of relationships when women stop using the pill, as odour perception plays a significant role in maintaining attraction to partners".