Baby boys more likely to die

LOS ANGELES, March 26 (UPI) -- A baby boy in a developing country is more likely to die than a baby girl, U.S. researchers said.

While Caesarean sections and neonatal intensive care units have helped more baby boys survive in developed countries, the gender gap in infant mortality exists in countries without these types of medical assistance, researchers from the University of Pennsylvania and University of Southern California found.

The study of 15 countries found that the gender gap in infant mortality was as high as 30 percent at its peak about 1970, but medical advancements since then have helped more baby boys survive.

"The marked reversal of historical trends indicates that at an age when males and females experience very similar lives, they are very different in their biological vulnerability, but how different depends on environmental and medical conditions," Eileen Crimmins, associate dean and professor at the USC Davis School of Gerontology said in a statement.

Boys are 60 percent more likely to be premature and suffer conditions arising from being born premature, such as respiratory distress syndrome, but they are also at higher risk of birth injury and mortality due to their larger body and head size, the researchers said.

The findings are published online in the Proceedings of the National Academy of Sciences.