Pill can lead women to choose the wrong man

Taking contraceptive pills can lead a woman to choose the "wrong" partner, a study suggests.

The Pill is thought to disrupt an instinctive mechanism that brings together people with complementary genes and immune systems.

By passing on a wide-ranging set of immune system genes, they increase their chances of having a healthy child who is not vulnerable to infection.

Couples with different genes are also less likely to experience fertility problems or miscarriages.

A man's smell signals, or pheromones, are derived from his Major Histocompatibility Complex cluster of genes which also help to build the proteins to resist disease.

From a woman's point of view, a man with an alluring smell is also likely to have suitable immune system genes.

But research carried out on 100 women provides evidence that the Pill can upset this process.

They were asked to "sniff" six male body odour samples from 97 volunteers and say which they preferred before and after taking the Pill.

Study leader Dr Craig Roberts, from the University of Liverpool, said: "The results showed that the preferences of women who began using the contraceptive pill shifted towards men with genetically similar odours."