Italian scientists have found that the contraceptive pill makes a woman less sensitive to smell at ovulation time � and they’re wondering whether this in turn may affect her libido.

Their study, involving 60 women aged 18 to 40, is published in today’s issue of the journal Human Reproduction.

A team from the University of Catania measured the women’s ability to detect six distinctive substances � anise, musk-ketone, clove, pyridine, citral and ammonia � at three defined times in their menstrual cycle.

It found that they were most sensitive to smell around ovulation.

The women then agreed to be prescribed oral contraceptives, and after three months their sensitivity to smell was tested again.

This time, however, there was no difference in sensitivity through different stages of the menstrual cycle, and the level of sensitivity was lower � nearly the same as that of the pre-menstrual phase when they were not taking the pill.

The researchers think this could be because the particular contraceptives used mimic the hormone levels at this phase of the menstrual cycle.

“Although our data have confirmed the existence of changes in olfactory sensitivity during oral contraceptive use,” said researcher Professor Salvatore Carusu, “we need to carry out further studies to investigate ways in which smell variations could vary a woman’s sexual life.”

Professor Lorraine Dennerstein of the University of Melbourne, who has been studying the psychosexual effects of contraceptive pills since the 1970s, said recent studies estimate 47 per cent of women stop using the pill.

One of the major reasons for stopping is adverse effects on moods and libido, she says, but as to the mechanism by which the pill affects libido, it’s early days in research.

“It deserves more scientific attention but it’s very difficult to get funding for research into sexuality,” she said.

Pharmaceutical companies had given higher priority to male sexual dysfunction than to helping the many more women who suffer from the condition, she said.