Prenatal exposure to smoking

Published Apr 22, 2008

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Researchers found that among more than 4 000 US women followed since the 1970s, those whose mothers had smoked during pregnancy were 21 percent more likely to have gone through menopause at any given age.

The findings suggest that maternal smoking during pregnancy may have a role in "programming" female children's eventual age at menopause, the researchers report in the American Journal of Epidemiology.

Dr. William C. Strohsnitter, of Tufts-New England Medical Centre in Boston, led the study.

Studies have long shown that women who smoke tend to go through menopause at a younger age. Researchers suspect that this is due to the effects of cigarette smoke on oestrogen production or on ovarian follicles, structures that produce a woman's eggs each month.

Women are born with a certain number of ovarian follicles, Strohsnitter and his colleagues note in their report, but little is known about the prenatal factors that might influence this number.

To investigate, the researchers used data from a study begun in 1975 to study the effects of prenatal exposure to DES, an oral oestrogen that was once prescribed to prevent miscarriages but was later found to be linked to a rare vaginal cancer in young women whose mothers used the hormone.

Strohsnitter's team focused on 4 025 study participants who were followed through 2001 and had complete information on their mothers' smoking habits. The women were born between 1939 and 1968.

By 2001, 15 percent of the study participants had gone through menopause. The researchers found that, at any given age, women whose mothers had smoked during pregnancy were more likely to have reached menopause.

This remained true even when the researchers accounted for other factors, including the women's own smoking habits and whether they had been exposed to DES in the womb.

It's possible, according to Strohsnitter and his colleagues, that prenatal exposure to tobacco smoke affects the early development of ovarian follicles.

However, they write, more studies are needed to understand how prenatal exposures may affect women's reproductive life.

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