Why Do Girls Live Longer Than Boys?

When does the gender gap start? In other words, do girls live longer than boys?

The disparity between male and female death rates exists in every age group, from infants through age 19—and beyond. "Our analysis of the gender difference in mortality among persons under 20 years of age suggests the existence of a 'male syndrome,'" writes Sheri L. Balsara, lead author of a recent study on pediatric mortality. "We observed an overall female survival advantage that starts early in life and exists across many diverse causes of mortality."

Actually, that survival advantage exists even before birth. While more male babies are conceived, male fetuses suffer from a higher death rate at every stage of gestation but one (the 24th week), according to another of the study's researchers, Chris Feudtner, a pediatrician at the Children's Hospital of Philadelphia.