Boys are 14% more likely
than girls to be born prematurely, and preterm boys have a greater risk of
disability and death than preterm girls, new research finds.
These disabilities range
from learning problems, blindness or deafness, to motor problems such as
cerebral palsy, according to the authors of six studies published in the journal
Paediatric Research in advance of World Prematurity Day.
"Baby boys have a
higher likelihood of infections, jaundice, birth complications and congenital
conditions, but the biggest risk for baby boys is due to preterm birth,"
research team leader Dr Joy Lawn, a professor and neonatologist and
epidemiologist at the London School of Hygiene & Tropical Medicine in
England, said in a journal news release.
"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," Lawn said. "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.
explanation for more preterm births among boys is that women pregnant with a
boy are more likely to have placental problems, preeclampsia [a serious
complication], and high blood pressure," conditions which are all
associated with preterm births, Lawn added.
However, the study authors
pointed out, preterm girls are more likely than boys to die in the first month
of life in some countries where girls receive less nutrition and medical care
The risk of disability and
death varies depending on where a preterm baby (less than 37 weeks' gestation)
is born, the investigators found. More than 80% of preterm infants in
high-income countries survive and thrive. The risk of death and disability is
greatest for those born at less than 28 weeks.
In middle-income countries,
the risk of disability for infants born at 28 to 32 weeks is double that of
those in high-income countries. In low-income countries, preterm babies are 10
times more likely to die than those in high-income countries. Death is twice as
likely as disability for preterm babies in these countries.
For the study, the
researchers analysed data from more than 15 million preterm babies worldwide.
Of the 13 million who survived beyond the first month of life, 4.4% had mild
disability and 2.7% had moderate or severe disability.
The largest number of
problems among preterm infants occurred in low-income countries in South Asia
and sub-Saharan Africa, where 2.2 million died and more than 600 000 had some
degree of disability, according to the study findings.
India had the greatest
number of preterm births at over 3.2 million. China had less than half that
number at 1.3 million, followed by Nigeria, Pakistan and Indonesia. The United
States recorded nearly 498 000 preterm births.
Malawi had the highest rate
of preterm births at 18.1 per 1 000 live births, the report noted.
The American Academy of Paediatrics
outlines health issues faced by premature babies.