Secondhand Smoke May Affect Women's Fertility Oct. 2, 2000 -- Even if a woman doesn't smoke, just being around a spouse, friend, or co-worker who does could significantly lower her chances of being able to get pregnant.

Many different conditions affect fertility, in both men and women. Smoking lowers a woman's fertility by about 20%, while men who smoke have lower sperm counts by about 16%, some research has shown. So a woman who smokes automatically lowers her fertility potential. But if her partner also smokes, or if she spends time breathing the smoke of others, it may take her much longer than she expected to get pregnant -- or so says a new study by British researchers.

Study author W. Christopher L. Ford, PhD, says a woman who smokes and is exposed to others' smoke can be expected to have the greatest delays in trying to become pregnant. "The passive smoke adds on as though you were smoking more cigarettes yourself," he explains.

In his study, published in the journal Fertility and Sterility, Ford found that women who smoked and had a partner who smoked were significantly less likely than others to become pregnant in six months of trying to conceive. Women smokers also had less success getting pregnant within a year of trying, and the delay increased along with the number of cigarettes smoked per day.

Women who did not smoke but were exposed to passive smoke were more likely than those with no such exposures to be unable to conceive within six months, but they had a higher likelihood of getting pregnant in a year of trying than women who smoked.

Previous studies have shown that chemicals in tobacco smoke can damage a man's sperm and can actually lodge in a woman's ovaries and interfere with her reproductive function. Although Ford's team didn't actually test the ovaries of women who'd been exposed to passive smoke to look for evidence of harmful tobacco byproducts, he says it makes sense that heavy exposure to passive smoke -- and, especially, living with a smoker -- could cause the same problems as actual smoking for women trying to conceive.