Boys are 14 percent more likely to be born preterm than girls. This is just one of the many findings outlined in a series of global studies conducted by almost 50 researchers at 35 institutions. In fact, baby boys are at a higher risk than baby girls for death and disability, including learning problems, blindness, deafness, and motor problems (such as cerebral palsy) because of a preterm birth. Generally, newborn boys are more likely than girls to develop infections, jaundice, birth complications, and other conditions as well. Seemingly, boys are the more vulnerable sex, at least from a biological perspective, early in life.

"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,” Professor Joy Lawn, M.D., PhD, a neonatologist and team leader of the new research, states in a press release. “Even in the womb, girls mature more rapidly than boys, which provides an advantage, because the lungs and other organs are more developed." Dr. Lawn is also an epidemiologist at the London School of Hygiene & Tropical Medicine (LSHTM).

Where A Baby Is Born Matters Most

As a partial explanation for more preterm births among boys than girls, Dr. Lawn indicated that women who are pregnant with boys are more likely to have placental problems, pre-eclampsia, and high blood pressure. Why these would occur more often with boy pregnancies is unclear, yet all of these conditions are more likely to result in preterm births. Where a child is born, though, seems to matter most in terms of a newborn’s survival and health.

In low-income countries, for instance, preterm babies are 10 times more likely to die than those in high-income countries. Death is twice as likely as disability in these countries. In particular, the possibility of newborn death is more likely in the low-income regions of South Asia and sub-Saharan Africa, where 2.2 million newborns died, and more than 606,000 had some degree of impairment following newborn complications.

"Three quarters of the 1 million babies who die each year from complications associated with prematurity could have been saved with cost-effective interventions, even without intensive care facilities," UN Secretary General Ban Ki-moon stated in a press release. The countries with the greatest number of preterm births were India (3,277,200) and China (1,315,000).

Meanwhile, in upper income countries, more than 80 percent of babies born under 37 weeks survive and thrive. Of the 11.7 million births in high-income countries, including the U.S., Canada, Australia, and most of Europe, 40,035 preterm babies died due to birth complications and infections, and another 147,000 were impaired. Major disability is most common for babies born at less than 28 weeks, and especially in those born under 25 weeks. Yet, even in upper income nations, infants who survive preterm birth face lifelong physical and intellectual disabilities. Babies born just a few days early are more likely to be re-hospitalized and have learning and behavioral challenges.

Although middle-income countries have made progress in terms of premature birth, the risk of disability for babies born at 28 to 32 weeks is still double that of high-income countries.


The reports, which were funded by the Bill and Melinda Gates Foundation, also focus on other factors that commonly and globally impact the health of newborns, including asphyxia complications during birth. Some 10 million babies are not breathing at birth often because of an obstructed labor or acute hemorrhage. Another 200,000 newborns are estimated to suffer from neonatal meningitis. Although estimates of severe neonatal jaundice are assumed to be underestimated, cases of this condition are said to affect another 588,000 newborns. In fact, jaundice accounted for at least 114,000 infant deaths, while another 63,000 babies survived but with moderate or severe disability. Finally, due to a lack of studies, the researchers could not estimate how many children develop disability as a result of sepsis, though this is another common and very serious condition.

Despite the generally higher survival and health risks encountered by boys, an entirely different issue may predict the health of infant girls: culture. For instance, in societies where girls routinely receive less nutrition and medical care than boys, they are more likely to die, rather than their male peers, after the first month of life despite any natural, biological advantage they may possess.

Source: Lawn JE, Blencowe H, Darmstadt GL, Bhutta ZA. Beyond newborn survival: the world you are born into determines your risk of disability-free survival. Pediatric Research. 2013.