A new study shows that when men smoked around their pregnant wives or girlfriends, their daughters tended to go through menopause about a year earlier than women of non-smoking dads.
Previous studies have shown that a woman's own smoking or that of her partner can affect the age of menopause. Now, "it seems that the effect of paternal smoking on daughters' reproductive life span is stronger than that of (her) husband smoking," study researcher Dr. Misao Fukuda, told Reuters Health in an email.
The researchers studied some 1,000 women in Japan. They found that women whose fathers smoked while they were in the womb stopped having their periods about 13 months earlier than those whose dads were nonsmokers.
It's not clear exactly why this is happening. Dr. Fukuda said it is possible that smoking around the time of conception could affect sperm cells or the embryo's development.
Researchers also can't say for sure that the effect is happening in utero, as opposed to when the child is growing up. Much more research is needed, they say.
The study was published in the journal Fertility and Sterility.