Although women become less likely to conceive as they age, men can become fathers well into middle age despite drops in their sperm counts, according to researchers.

Reviewing the cases of 441 couples attempting in vitro fertilization (IVF), investigators found that the male partner's age had no bearing on whether a couple was able to conceive through egg donation. The findings were published in the April issue of the American Journal of Obstetrics and Gynecology.

During IVF, the man's sperm is used to fertilize the donated egg in a test tube. But while research shows men's sperm production may decline with age, it has been unclear how a man's age affects his ability to have children. Men have become fathers well into old age, but there is evidence that sperm quality falls over time, possibly affecting fertility.

The study findings suggest that although sperm number and quality may decline with age, fertility does not. Among men older than 50, 58% of fertilization attempts were successful--on par with the 60% rate among younger men, report Dr. Richard J. Paulson and his colleagues at the University of Southern California in Los Angeles.

More importantly, the man's age did not affect whether the couple had a baby. Among the older men, 28% of those who tried IVF once became fathers, while there was a 63% birth rate among those who tried three times. These overall success rates, according to Paulson's team, were similar to those of the younger men.

Not surprisingly, the researchers did find that the men's sperm count and sperm movement dipped with age. However, the man's age played no role in whether a couple had a baby.

While there were no differences in birth rates, the study did not look at the health of the older men's children after they were born. As men age, Paulson notes, they may become more likely to pass on genetic abnormalities.

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