Male infertility may stem from in utero chemical exposures
Scientists report being able to take the measure of a man — or at least his ability to father children — with a $40 pair of measuring calipers. They use the instrument to carefully assay the distance between his genitals and anus.
In a new study, this distance proved a potent predictor not only of sperm count but also of semen quality — the concentration of sperm as well as sperm motility and shape. Of these, sperm count correlated best with anogenital distance, or AGD. In fact, “AGD is now the strongest predictor of sperm count that we know of,” says Shanna Swan, a reproductive epidemiologist in the University of Rochester’s Department of Obstetrics and Gynecology.
No one knows what triggered the reproductive changes for which AGD serves as a marker, Swan says. A number of environmental factors — including a mother’s smoking or obesity — appear able to perturb fetal androgen levels. But in 2005, Swan’s group