According to new research, baby boys are 14 percent more likely than girls to be born prematurely. And once born, premature boys face greater risks of disability and death than preemie girls born at the same age.

"For two babies born at the same degree of prematurity, a boy will have a higher risk of death and disability compared to a girl," said researcher Dr. Joy Lawn of the London School of Hygiene & Tropical Medicine who led a series of six studies on premature infant health. "Even in the womb, girls mature more rapidly than boys, which provides an advantage, because the lungs and other organs are more developed," she explained.

"This is a double whammy for boys," Dr. Lawn continued. "It's a pattern that happens all over the world."

For the study, the researcher team analyzed health records from more than 15 million preterm babies worldwide. Slightly more than half of these preemie babies were male. Of the 13 million who survived beyond the first month of life, 4.4 percent had mild disabilities such as learning problems and 2.7 percent had moderate or severe disability such as blindness, deafness, or cerebral palsy.

In wealthier countries, more than 80 percent of premature infants survive and thrive, although even babies born a few weeks prematurely are more likely to have difficulties with learning and behavior. In poorer countries, preterm babies are 10 times as likely to die as those born in more developed countries. In South Asia and sub-Saharan Africa, 2.2 million preemie babies died within the study period while more than 600,000 faced some degree of disability.

The results of the studies were released in conjunction with World Prematurity Day on Nov. 17.

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