Red Meat May Harm Sons' Sperm

Men whose mothers ate a lot of beef during pregnancy have lower sperm counts, finds a study attempting to track the effect of growth hormones fed to cattle. While the specific chemicals weren't identified, sons of pregnant women who ate beef more than seven times a week were three times as likely to have sperm counts below the fertility threshold.

Although men don't start producing sperm until adolescence, lead researcher Shanna Swan says, "The fetus and young children are particularly sensitive to exposure to sex steroids." Growth promoters were banned in Europe in 1988 but some are still used in the U.S. (More medicine stories.)