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Boy Decline

May 7, 2007

Fewer baby boys are being born. Scientists are looking for the reason.


Are boys becoming a rarer breed? I’m Bob Hirshon and this is Science Update.

Since 1970, over a quarter of a million fewer boys were born in the US and Japan than expected. This according to a study led by epidemiologist Devra Lee Davis at the University of Pittsburgh Schools of the Health Sciences. What’s more, she says an increasing proportion of fetal deaths are male. The data alone can’t say why.

DEVRA LEE DAVIS (University of Pittsburgh):
But I think it’s pretty clear that whatever’s going on here is principally working through the male. Fathers are more important because the fertilizing sperm determines the sex of an embryo.

Davis says some evidence suggests that environmental contaminants such as pesticides and organic solvents may be to blame. She says these chemicals may damage fragile Y-chromosome sperm and interfere with male development.

I’m Bob Hirshon, for AAAS, the science society.