Tuesday, May 08, 2007

Fewer Baby Boys Born in U.S. and Japan

We all know the birth rate has been falling in the U.S. But what you might not know - the rate of boys born each year is declining faster than that for girls. Yeah, great, another item to enter into the gender wars, one point to those decrying the plight of our testosterone-packed progeny. This I can say without apology owing to my doctoral dissertation on gender discrimination. So, back to this falling baby boy thing. It's been going on for over three decades. And now, thankfully, we are hearing about it from media reports fueled by the recent publication of data on the online edition of Environmental Health Perspectives. How bad is it? Whereas we could have expected 105.5 boys for every 100 girls some thirty years ago, now it's around 104.6 boys. Gee, all this fuss over one boy change? Doesn't sound like much, but the annual drop translates over the past 30 years into a shift of over 135,000 from male to female births. In English, it means we've lost a good number of boys.

So why? What's going on? Probably a variety of factors, for one, environmental toxins. Researchers have long implicated the paternal link, listen up, dads-to-be. Read up on some interesting case studies of fewer baby boys born to male fathers (but not mothers) involved in large-scale industrial (read "toxic" accidents). For now, moms, you may be smiling, but we too, may also bear some responsibility for this boy thing, probably through prenatal exposure to toxins as well (tuna anyone??), but it's more of a guess than a fact right now.

Okay, so the real title of this new study - Declines in Sex Ratio at Birth and Fetal Deaths in Japan and U.S. Whites, but not in African Americans. But not for African Americans! It pays to read, well, the original article! As it turnsout the sex ratio of birth is not declining for African Americans, it is actually increasing. Although the gap is much smaller (103.1 to 103.2) than that for Whites (105.9 to 105). Speculative answers include earlier puberty onset among African Americans. I'm sure there are some socio-cultural factors hanging in there somewhere.

Good news! You can read the entire article for free, yes, free. Check out the cool graphs at the end. The authors refer to some curious studies involving sex ratios and toxins. Reason enough to consider your inner tree-hugger. Get back to me with your observations.

Davis, Webster, Stainthorpe, Chilton, Jones, and Doi. (2007). Declines in Sex Ratio at Birth and Fetal Deaths in Japan and U.S. Whites, but not in African Americans. Environmental Health Perspectives Online, April.

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