Extremely premature babies considered to be on the cusp of viability are much more likely to survive and evade illness today than they were 20 years ago, according to a study published in the Journal of the American Medical Association. This increase in positive outcomes is likely due to improvements in medical treatments for these babies and their mothers over the past two decades.
The study was conducted between 1993 and 2012 and included nearly 1,100 infants from Rochester, Buffalo and surrounding areas. It found increases in survival rates of infants born 23 or 24 weeks into a pregnancy. While babies born at this early stage of pregnancy still have many health problems after birth, babies born as little as a one week later (between 25 and 28 weeks) experienced a decrease in several illnesses that typically occur in extremely premature infants.
“Survival, particularly among the smallest and least mature infants, continues to improve,” said Carl D’Angio, M.D., a study author and professor of Pediatrics and Medical Humanities & Bioethics at the University of Rochester School of Medicine and Dentistry. D’Angio, who treats premature infants at UR Medicine’s Golisano Children’s Hospital, is the principal investigator of a combined University of Rochester-University at Buffalo research site that enrolled patients in the study.
Survival, particularly among the smallest and least mature infants, continues to improve.
The continuing improvement in survival among the least mature infants may be due, in part, to the significant increase in the use of corticosteroids to speed up lung development in the fetuses of mothers at risk of delivering early. In 1993, less than a quarter of mothers who delivered extremely premature infants received the steroids; the number jumped to 87 percent in 2012.
Mothers at risk of delivering at 22 to 24 weeks of pregnancy were also much more likely to have a cesarean delivery and to be treated with antibiotics during pregnancy in recent years than they were at the beginning of the study. Cesarean deliveries may minimize the trauma of birth, which may boost a baby’s chance of survival. Prenatal antibiotics are meant to prevent transmission of infections between mom and baby; however, there were no changes in rates of infection over the course of the study.
Together these findings suggest a progressive increase in physicians’ ability to treat extremely premature infants who are near “the limit of viability.” With continued improvements in care and outcomes, that “limit” has slowly dropped to earlier times in pregnancy.
The decline of health problems in slightly more mature preemies may also be attributed to improved medical care after birth. The drop in late onset sepsis, a whole body infection usually contracted through medical care, could be a result of enhanced hygiene practices and reduction of invasive treatments, such as intubation, in preemies. The study also found a shift toward less aggressive ventilation, with fewer infants having breathing tubes placed in the delivery room and fewer infants receiving corticosteroid treatment during their hospital stay.
Much like other health issues, “neurodevelopmental abnormalities continue to be common among the smallest infants,” said D’Angio, “but rates are improving among larger – but still very small – infants.” Premature infants born after 26 weeks of pregnancy were less likely to experience conditions that cause bleeding in the brain or damage to brain tissue that often leads to movement disorders and developmental delays. The investigators are continuing to monitor the effect of these improvements on the long-term outcomes for the children in this study.
While the results of this study are encouraging, D’Angio warned, “We have come a long way, but still have a journey ahead of us.” The numbers are improving, but infants born before 27 weeks of pregnancy who survive without major illness are still the minority.
The study was led by Barbara J. Stoll, M.D., chair of pediatrics at Emory University School of Medicine and was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The Neonatal Research Network (NRN), a group of academic medical centers across the U.S., collected data on medical interventions and outcomes from approximately 35,000 infants born between 22-28 weeks of pregnancy.
The study authors note that NRN research sites are not representative of the level of care and outcomes typical of the average medical facility, as they were chosen for their special expertise in caring for high-risk mothers and extremely premature infants. Therefore, more national studies like this one must be done to further understanding of the underlying causes of poor outcomes and to continue to define “best practices” of care for the most immature infants.