The study involved female mice injected with environmental toxins found in cigarette smoke before they became pregnant and while they were nursing.
Though the mice's litter size was not affected by the smoke toxin exposure, ovarian function in the female offspring was.
Lead researcher Andrea Jurisicova, PhD, says she hopes the findings in mice will spur further research examining the role of cigarette smoke and exposure to similar environmental toxins on fertility.
"We want to raise concerns. We don't want to spook anybody," Juriscova tells WebMD. "But this research does suggest that a woman who smokes may be affecting her future offspring's fertility without knowing it."
Smoking and Fertility
Maternal smoking is linked to a wide range of pregnancy complications, including low birth weight, placental problems, and premature delivery.
Previous studies have also suggested a link between cigarette smoke exposure in the womb and impaired fertility later in life in both women and men, but the reasons for the association have not been known.
In an effort to explain the association, Juriscova and colleagues injected female mice with the environmental toxin polycyclic aromatic hydrocarbons (PAHs) prior to pregnancy and after birth while they were nursing to mimic the effects of cigarette smoke exposure.
The researchers note that most women stop smoking once they find out that they are pregnant.
The researchers found that the daughter mice had about two-thirds fewer ovarian follicles Each ovarian follicle contains a single egg, so fewer follicles means fewer eggs.
Further research indicated that the chemical exposure triggered the increase of a protein associated with cell death, mediated through a receptor known as Ahr.
Further experiments involving human ovarian tissue samples showed a similar sequence of events.
The study is published Nov. 21 in the online issue of The Journal of Clinical Investigation.
Sons Face Similar Risks
In a separate study, published earlier this month, University of Aberdeen fertility researcher Paul Fowler, PhD, and colleagues reported similar findings in men.
Specifically, Fowler and colleagues showed that sons born to mothers who smoked during pregnancy had lower levels of a gene called DHH, which promotes testicular growth.
DHH expression in these men was roughly half that seen in men born to mothers who did not smoke during pregnancy.
Small testicles are linked to low sperm counts, so this could explain how maternal smoking affects the future fertility of unborn boys, Fowler tells WebMD.
"We now have a gene that explains what we have seen in population studies," he says.
By Salynn Boyles
Reviewed by Louise Chang
©2005-2006 WebMD, Inc. All rights reserved