On call: Male fertility

On call

Male fertility

Published: March, 2014

Q. I've heard that men are making fewer sperm cells than they used to, and birth rates may suffer. What's the latest information?

A. In the early 1990s, scientists in Europe raised worldwide concern when they reported a dramatic 42% fall in sperm counts between 1940 and 1990. Almost immediately, American doctors entered the debate; most reported that sperm counts on this side of the Atlantic were holding steady. And a recent analysis confirmed the reassuring news. Researchers evaluated 29 American studies performed between 1938 and 1996. If the results were pooled, they seemed to show a fall in sperm counts. But when the scientists took geographic variation into account, they found that American men are producing as many sperm in the '90s as they did in the '30s and '40s.

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