TUESDAY, Oct. 30, 2001 (HealthDayNews) -- The way to a man's heart may be through his stomach, but the clear path to a woman's passion may be through her nose.
A woman's sense of smell seems intimately tied to her desire for sex, claims a group of Italian scientists.
What's more, they say birth control pills may put a damper on a woman's desire by affecting her sense of smell.
"After many years of studies on sexuality dysfunctions, we found that many factors influence a woman's desire, one of which could be the sense of smell," says study author Salvatore Caruso, professor of gynecological science at the Ospedale S. Bambino in Catania, Italy.
While it has long been thought that men can become sexually stimulated by the scent of a fertile woman, Caruso says the opposite also is true: A woman may have an exaggerated sense of smell when her reproductive hormones are peaking in mid-cycle, just before ovulation -- a time when a woman is most likely to conceive.
"We believe that this increased sense of smell could serve a fertility purpose as it increases the desire in women to mate, " Caruso says.
So, could factors that affect a woman's hormonal fluctuations also affect her sense of smell and ultimately her desire for sex and even her fertility?
Caruso designed a study to prove they could.
But not everyone agrees with the basic premise. Indeed, Dr. Gianpiero D. Palermo, a fertility expert at New York City's Weill Cornell Medical Center, says a few too many leaps of faith crisscross the foundation of the theory.
"We know from many studies that sexual desire may have little to do with fertility," Palermo says. Women who are not sexually stimulated at all -- victims of rape, for example -- can easily become pregnant, while those with a mad, passionate desire for sex may have great difficulty conceiving or not be able to conceive at all, he says.
"Like the sense of touch, the sense of smell may play some role in exciting the libido, but to believe it is linked to fertility, or that sex drive is linked to fertility, this requires quite a leap in logic," Palermo says.
Nevertheless, Caruso and his team set out to discover if there is cyclical nature to a woman's sense of smell, one linked to the hormonal fluctuation of the reproductive cycle, and whether factors that affect those fluctuations -- like birth control pills -- also affect the sense of smell and ultimately the desire for sex.
The researchers engaged 60 women, aged 18 to 40, none of whom were taking birth control pills. Each woman was exposed to a series of smells at various times during a single reproductive cycle. Exposure occurred during the follicular phase (five to eight days after the onset of bleeding), the periovular phase (mid-cycle, just before ovulation, on days 13 to 16) and during the final luteal phase (days 18 to 23), just before the onset of bleeding.
The scents used included anise, musk-ketone, clove, pyridine, citrus and ammonia, because they "stimulate the majority of the range of smells that we can all normally sense," Caruso says.
The researchers found that a woman's sense of smell is strongest during the periovular phase, just before ovulation, the study says.
Subsequently, the women were given one of two slightly different formulations of birth control pills for three months. Half took pills containing ethinyloestradiol and gestodene, and the other half used a formulation containing ethinyloestradiol and dosogestrel.
After three months, the women were subjected to another round of scent testing on days 7, 14 and 21 of a 28-day reproductive cycle.
This time, the researchers say the women's sense of smell remained the same during all three phases of the cycle. Their sensitivity levels matched those documented during the luteal phase of the non-pill cycle.
Birth control pills did dampen the sense of smell, reducing it to a level equal to that which occurs after the point in a woman's cycle when she is no longer fertile, the researchers conclude. Perhaps not coincidentally, that's also a time when natural mating desires are reduced, and sex drive is less intense, Caruso says.
Earlier studies have shown that up to 47 percent of women who are prescribed birth control pills stop taking them, citing a negative impact on sex drive as a major reason.
Although Palermo says the study, reported in the current issue of the European journal Human Reproduction, was well done, he says he still has trouble buying the basic premise that sex smells like fertility.
"The hormone levels found in the pill may reduce the sense of smell, but I don't think there is any evidence to show that a reduced sense of smell results in a reduced sex drive and certainly not a reduction in the ability to get pregnant," Palermo says.
But Caruso says he doesn't believe the link between hormones, sex and smell are a fluke; however, he concedes that there are many miles to go, and many smells to be sniffed before any concrete conclusions can be drawn.
What To Do
To learn more about the sense of smell, visit the Sense of Smell Institute.
For more information on sex and smells, check these articles from ABCNews.com and the Social Issues Research Center in England.
