Contraceptive pills taken by tens of millions of women around the world can disrupt the innate ability to sniff out a genetically compatible partner, a study has found.
Normally women are instinctively attracted, via their sense of smell, to men who have a dissimilar genetic makeup.
Overly similar gene profiles can result in difficulty trying to conceive a child, an increased risk of miscarriage and a weaker immune system, earlier research has shown.
A group of about 140 genes in an area called the Major Histocompatibility Complex (MHC) - which helps build proteins involved in the body's immune response - also plays a key role in odour through interaction with skin bacteria.
How these genes are expressed can help determine which individuals, unknowingly following their nose, find us attractive.
A team led by Craig Roberts at the University of Newcastle, England, conducted an experiment to find out if taking the pill influences odour preferences.
One hundred women were asked to indicate which of six male body odour samples they found most attractive, both before and after starting to take the contraceptive.
The male scents were drawn from 97 volunteers.
"The results showed that the preferences of women who began using the contraceptive pill shifted toward men with genetically similar odours," said Mr Roberts.
The research not only suggested that taking the pill could induce women to pick Mr Wrong, but pointed to the potential to wreak havoc in couples.
"It could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odour perception plays a significant role in maintaining attraction to partners."
Oral contraceptives combine two hormones, oestrogen and progestogen, to inhibit normal female fertility.
The study was published in the British journal Proceedings of the Royal Society B: Biological Science.
