A mother?s high beef consumption while pregnant was associated with lower sperm counts in her son, according to a study led by researchers at the University of Rochester.
Researchers sought to examine the relationship between semen quality and long-term risks from growth hormones and other chemicals in beef.
While the study results revealed a significant link between the lowest sperm counts and mothers who were the highest beef consumers (seven or more beef meals per week), researchers could not pinpoint hormones, pesticides or other environmental chemicals in the animal fat as a direct cause.
“What we?re really doing here is raising an issue,” said Shanna H. Swan, Ph.D., director of the Center for Reproductive Epidemiology at the University of Rochester Medical Center and lead author of the study. “The average sperm concentration of the men in our study went down as their mothers? beef intake went up. But this needs to be followed carefully before we can draw any conclusions.”
The study is being published March 28 in the journal Human Reproduction.
It?s important to note that all of the 387 men in the study were able to conceive a child without medical assistance, so although sperm counts were low in some cases none of the men were actually infertile. Yet among the 51 men whose mothers were the highest beef eaters, almost 18 percent had sperm counts classified by the World Health Organization as “sub-fertile” (20 mill/ml or lower). By comparison, sperm concentrations were 24 percent higher for men whose mothers ate less beef, and only about 5 percent had sperm counts that could be classified as sub-fertile.
The concern, Swan said, is that high beef consumption by pregnant women may alter sperm production of the male fetus in utero, particularly at the end of the first trimester during the critical period for testicular development. Although sperm production occurs in stages — prenatal, during puberty, and into adulthood ? the most important stage for developing semen quality occurs in the womb, Swan added.