Extremely preterm infants, those born before the 28th week of pregnancy, are surviving in greater numbers and escaping serious illness, according to a comprehensive review of births in a National Institutes of Health research network. RTI International has served as the data coordinating center for the network since 1998 and co-authored the study.
The study, published in the Journal of the American Medical Association, reviewed the birth records of more than 35,000 premature infants born from 1993 to 2012 in 26 U.S. centers participating in the Neonatal Research Network, a program funded by NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
Among the major findings:
- Infants born at 23 and 24 weeks survived in greater numbers over the 20-year period. Of those born at 24 weeks, for example, only 52 percent survived in 1993 while 65 percent survived in 2012.
- A higher number of premature infants survived without major illnesses. For infants born at 27 weeks, for example, survival without major illness increased from 29 percent in 1993 to 47 percent in 2012.
Although the rates of many serious health problems declined, notably late-onset sepsis, the researchers saw an increase in the rate of bronchopulmonary dysplasia, a complication often resulting from respiratory therapy. Improvements in respiratory care appear to have saved many infants who otherwise may have died. Nonetheless, the infants' under-developed lungs often sustain damage.
For more than 20 years, NICHD's Neonatal Research Network, with RTI as its longtime data coordinating center, has made seminal contributions to developing the evidence base for better clinical management of extremely preterm babies.
"Such research has led to real improvements in survival and outcomes," said Nellie Hansen, senior research statistician at RTI and second author of the paper.
More than 450,000 premature babies are born each year in the United States. The boost in survival may be attributed to advances in maternal and newborn care, such as the increased use of antenatal steroids - these drugs are given to women at risk for preterm birth to help stimulate lung development in the fetus. In 1993, physicians gave antenatal steroids to only 24 percent of women at risk for delivering too early, according to the study. A 1995 NIH consensus statement on antenatal steroids led to the widespread use of the treatment. By 2012, doctors were giving the steroids to nearly 87 percent of at-risk pregnant women included in the study.
The study authors noted that the increase in survival of extremely preterm infants parallels an increase in cesarean sections in this age group. Such surgery may result in a less traumatic birth for the infant and therefore may contribute to survival.
The study authors also stressed the need for continued research on the care of extremely preterm infants. Although survival has increased over the past two decades, including survival without major illnesses, preterm birth in the United States still poses a substantial burden to families and society at-large, they wrote.