That's because men don't usually get this news flash until they're looking through a microscope at a batch of fugly sperm with no sense of direction. Swain, a 37-year-old IT professional in Dallas, wishes he had heard sooner. "Who cares if the baby is born with six fingerswe can't get that far," he says. "I'd be thrilled to have that problem." His wife is four years younger than he is, and they decided to wait. "What I did was let her clock be the one in control," Swain says. "I would have been happy having kids five, six years ago, but she just wasn't ready. The female clock seems to dominate the conversation."

But don't expect sweeping social change anytime soon. "Tell a man he's got a chance of having kids with genetic abnormalities, and it's like he's going through the stages of the acceptance of death," says Dr. Harry Fisch, a professor of urology and the author of The Male Biological Clock. "They'll say, 'I'm losing my manliness, my sexual ability.' To them it all comes under the same umbrella."

The good news is that no one, not even Malaspina, is suggesting that older men eschew the joys of fatherhood. But if you're a younger guy who hasn't thought twice about postponing it, be forewarned: The female of the species is about to get her just rewards. That bell tolling? It's for you.

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