For the sake of your future child, don't smoke. Be wary of alcohol. Eat for three: yourself, your unborn baby, and your spouse.

And try to get your wife to follow the same healthy lifestyle. While humanity has long known that toxicants can undermine male fertility, common thinking was that the postconception health of the fetus was solely the province of the mother. It turns out that the health habits of both parents can affect the odds not only for conception but for miscarriage, birth defects, and childhood cancer. New research confirms that potential medical problems for offspring can ride sperm from the father all the way into the egg.

In fact, findings suggest that men who wish one day to sire healthy offspring should start thinking more like a savvy pregnant woman. Though the pregnancy-related warnings on wine labels and cigarette packs target women only, healthy pregnancies involve the teamwork of a relay race, and before conception the future father has a turn carrying the baton.

Gurney Williams III writes and lectures frequently on health and science issues.

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