Weight may affect men’s sperm, study says

PHILADELPHIA – Beer bellies may take a toll on men below the belt, not just around it.

Men who weigh too much are more likely to have poor sperm quality, research on nearly 1,600 young Danish men has found. Being too thin is a problem, too.

Women don’t get off the hook. Though it’s long been known that very overweight women have trouble conceiving naturally, a large new study confirms they also are less likely to become pregnant even when embryos are fertilized in lab dishes and placed in their wombs.

“Among the severely obese, we saw significantly reduced implantation and pregnancy rates,” said Dr. David Ryley of Beth Israel Deaconess Medical Center in Boston. He presented results of the women’s study this week at a meeting of the American Society for Reproductive Medicine.

The sperm study was done by doctors at various hospitals and universities in Denmark and published in the October issue of the reproductive society’s journal, Fertility &Sterility.

Sperm counts and sperm concentrations were 28.1 percent and 36.4 percent lower, respectively, in underweight men. The same measures were 21.6 percent and 23.9 percent lower, respectively, in overweight men.

“It may be an alteration in hormonal values,” said Dr. Anthony Thomas, a Cleveland Clinic urologist who is president of the Society for Male Reproduction and Urology and was not involved in the study.

Men produce and need a certain amount of the female hormone estrogen. Fat cells produce estrogen, so too much or too little of it may be a problem.

“There’s a balance, and that balance is the milieu in which sperm develops,” Thomas said.

Other research suggests that smoking and heavy alcohol use also harm sperm production, he said. The new study is a reminder that doctors should always check a man for signs of infertility when couples are having trouble getting pregnant because the problem is just as likely to involve men as women.

“It’s not uncommon for a man to come in after his wife has had a million tests” and then is discovered to have sperm problems, Thomas said. “It’s probably one of the first things a doctor should do.”