A man smokes a cigarette in central London, February 1, 2010.SUZANNE PLUNKETT/REUTERS
If men smoke when their partners are pregnant, their daughters may end up reaching menopause about a year earlier than their peers, according to a study.
Previous research has found that a woman's own smoking habits, as well as those of her partner, may also have an impact on her fertility and may precipitate the point at which she can no longer get pregnant.
"It seems that the effect of paternal smoking on daughters' reproductive lifespan is stronger than that of (her) husband smoking," said Misao Fukuda, at the M&K Health Institute in Ako, Japan, in an e-mail.
Dr. Fukuda said it is possible that smoke exposure around the time of conception could affect either the fertilizing capacity of sperm cells or early embryo genesis - or both.
For the study, published in Fertility and Sterility, Dr. Fukuda and colleagues questioned more than 1,000 postmenopausal Japanese women who were visiting clinics for gynecologic exams. They asked them how old they were at menarche and menopause, as well as whether they or their husbands smoked.
The women were also asked if their own mothers or fathers had smoked when the mothers were pregnant.
Overall, the mean age at menopause was 51 - but women who were smokers themselves hit menopause an average of about 14 months earlier than those who didn't.
When their husbands smoked, they went through menopause about five months earlier, though the results were not statistically significant.
But women whose fathers smoked while they were in the womb stopped having their periods about 13 months earlier than those whose fathers were non-smokers, the study found.
Not enough mothers smoked for the researchers to determine how that influenced their daughters' puberty or menopause - and smoking by fathers didn't appear to affect the timing of menarche.
The researchers also said they weren't sure, based on the study, whether the effect of a father's smoking happened before their daughters were born, or whether it happened when they were children.
"The whole issue of teasing apart prenatal effects versus childhood [effects]is really hard to do," said Jennifer Ferris, who has studied the link between secondhand smoke and puberty at Columbia University, but was not involved in the study.
"Most of the time, if the woman's smoking when she's pregnant or the father's smoking when she's pregnant, that child will also be exposed during childhood."
In addition to the effect on sperm cells described by Dr. Fukuda, Ms. Ferris said that chemicals from cigarette smoke may alter glands in the brain that produce reproductive hormones, but that more research is needed.
"It would be nice to see more studies looking at paternal smoking because that still may be more common than women smoking during pregnancy," she added.
Reuters