Smoking and exposure to secondhand smoke is tied to infertility in women and early menopause, according to a new study.
Compared to women who never smoked and those exposed to the least secondhand smoke, women who smoked or were exposed to the most secondhand smoke were more likely to have problems getting pregnant and more likely to enter menopause before age 50, researchers found.
Andrew Hyland of the Roswell Park Cancer Institute in Buffalo, New York, who led the research, said earlier studies had linked smoking to reproductive issues in women, but few had looked at links between secondhand smoke and infertility and early menopause.
"The literature really wasn’t clear – particularly with secondhand smoke," Hyland told Reuters Health.
Hyland and colleagues analyzed data on 88,732 US women who enrolled in the Women's Health Initiative Observational Study between 1993 and 1998, when they were between the ages of 50 and 79.
Based on questionnaires the women completed at the start, about 15 percent met the criteria for infertility, which is the inability to get pregnant for at least a year. About 45 percent also met the criteria for early menopause, which occurs before age 50.
Compared to women who never smoked, researchers found that those who reported being active smokers at some point in their lives were 14 percent more likely to have infertility and 26 percent more likely to enter menopause early.
Women who smoked the most reported entering menopause about two years earlier than women who didn't smoke, the researchers report in the journal Tobacco Control.
Women who never smoked but were exposed to the most secondhand smoke were 18 percent more likely to have problems getting pregnant and to enter menopause at an early age, compared to women who never smoked and were exposed to the least amount of secondhand smoke.
While an 18 percent increased risk may seem modest, Hyland said it's large considering infertility and early menopause are not uncommon.
"There are a lot of events that could be attributed to these exposures," he said.
Hyland cautions that the study can't prove smoking causes these problems. The research team did, however, adjust the data to account for other factors that would be tied to infertility and early menopause.
The study also can't say what may underlie the link between smoke exposure and infertility and early menopause, but Hyland said other research suggests that smoke exposure may affect hormone levels.
It appears the association is driven by smoke exposure throughout a woman's lifetime, he said.
"As for a recommendation to clinicians, you should advise women of reproductive age to limit their exposure to minimize these outcomes," said Hyland.