Survival rate may be improving for extremely preterm infants born between the 22nd and 24th week of pregnancy

Study also shows surviving infants have fewer neurological impairments

A premature baby drinks from a bottle

RESEARCH TRIANGLE PARK, N.C.— Very early preterm infants are more likely to survive than in previous years, and the survivors are less likely to have neurological problems, according to an analysis of records from a national research network on newborn babies. RTI International serves as the data coordinating center for this research network and helps design, implement, manage and analyze the data for all studies conducted by the network.

The study is published in the New England Journal of Medicine.

Researchers found that of the more than 4,000 extremely preterm infants born at 11 sites within the network from 2000 to 2011, survival rates increased from 30 percent to 36 percent. The proportion of survivors who did not have a neurological or developmental impairment increased from 16 percent to 20 percent. The proportion of infants who survived with a neurological impairment did not change.  The authors theorize that these improvements are a result of advances in the care provided to expectant mothers and their newborns.

Infants in the study were born between the 22nd and 24th week of pregnancy, far earlier than the 40 weeks generally expected for a pregnancy to reach term.  Those born from 2008 to 2011 had the lowest death rate (64 percent). From 2004 to 2007, the death rate was 70 percent, unchanged from 2000 to 2003.

“RTI has been working to improve the survival rates and wellbeing of extremely preterm infants for years through our partnership with the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network,” said Carla Bann, Ph.D., co-author of the study and statistics and psychometrics fellow at RTI.

“It’s gratifying to see the improvements made to increase the survival rate of these babies, though we realize that more research is needed to further develop the evidence base  for improving outcomes in extremely premature newborns,” added Abhik Das, Ph.D., co-author and principal investigator for the data coordinating center at RTI.

Providing care to infants born so early is often challenging. Physicians and family members may be reluctant to expose an infant to sometimes painful life-support procedures. Those offered active treatment may survive, but may have hearing loss, blindness, cerebral palsy, and severe intellectual disability.

The study provides important information for physicians and family members planning the care of these extremely fragile newborns. However, since the results encompass trends for a large number of infants at multiple research sites, they should not be used to predict the outcome for an individual child because no single source of information can precisely predict an individual baby’s chances of survival or disability. Still, the findings do provide important information that physicians and family members can consult to help determine treatment strategies.

The study authors wrote that, in the past, many experts had feared that advances leading to improvements in survival among extremely preterm infants might also result in a higher proportion of infants with disabilities. However, in the current study, researchers found that across all three time intervals, the percentage of infants who survived with a disability did not change significantly.

The authors wrote that the increases in overall survival and survival without neurological harm likely result from improvements in the care given to mothers and newborns. One potential contributing factor is the wider use of antenatal steroids. These drugs, which are given to women at risk for preterm birth, help the infant’s lungs mature, leaving the infant less reliant on ventilation therapy, which can sometimes damage the lungs and lead to infections.

Learn more about our work with the Neonatal Research Network