Major complications have decreased and survival has improved for extremely premature infants born over the past 20 years, according to research from the National Institutes of Health Neonatal Research Network, which includes McGovern Medical School (a part of UTHealth) and UT Physicians.
The results were published online in the Journal of the American Medical Association.
According to the Centers for Disease Control and Prevention, preterm birth — birth before 37 weeks of gestation — affected more than 450,000 infants in 2012, or 1 in every 9 births. Preterm-related causes of death accounted for 35 percent of all infant deaths in 2010, the largest single cause. Preterm birth is the leading cause of long-term neurological disabilities in children. It cost the United States heath care system more than $26 billion in 2005.
The study examined 34,636 infants considered extremely premature — 22 to 28 weeks of gestation — that were born at 26 network sites between 1993 and 2012. They weighed between 14.1 ounces to 3.3 pounds. One-fourth of the infants were from multiple births.
The study was led by Barbara J. Stoll, M.D., dean and H. Wayne Hightower Distinguished Professor of McGovern Medical School.
“Our findings are cautiously optimistic and demonstrate that progress is being made and outcomes of the most immature preterm infants are improving,” Dr. Stoll says. “Perhaps the most important and most optimistic finding is a significant increase in survival to hospital discharge without major in-hospital neonatal morbidities. Although our study did not report long-term outcomes after hospital discharge, we are hopeful that the increase in survival without major morbidity will translate into improved long-term outcomes for these vulnerable extremely preterm infants.”
Kathleen Kennedy, M.D., co-author, UT Physicians pediatrician, and the Richard W. Mithoff Professor of Pediatrics, says, “This study provides important information for clinicians to use in counseling parents about the expected outcomes for their infants and it also provides outcome data from highly respected academic neonatal units that can be used as benchmarks for other units.”
Researchers found that survival increased for infants at 23 weeks gestation from 27 percent in 2009 to 33 percent in 2012, and those at 24 weeks from 63 to 65 percent. There were small relative increases of survival for infants at 25 and 27 weeks gestation and no change for infants at 22, 26 and 28 weeks.
Survival without major complications increased approximately 2 percent per year for infants at 25 to 28 weeks gestation, one of the most important findings of the study. There was no change for infants at 22 to 24 weeks gestation, which underscores the continued need for interventions to improve outcomes for the most immature infants, the authors wrote.
Major complications include severe necrotizing enterocolitis (severe bowel disorder), infection, bronchopulmonary dysplasia (chronic lung disease), bleeding in the brain, ischemic brain injury and eye changes that may lead to decreased vision and even blindness. While rates of most major complications dropped, the rate of bronchopulmonary dysplasia increased from 2009 to 2012 for infants born at 26 to 27 weeks of gestation.
“As survival rates increase over time, and more of the most immature fragile babies are surviving, it is not surprising that a higher proportion of that group who survive will develop bronchopulmonary dysplasia and other complications,” Dr. Kennedy says. “But when you count all babies, there has been a steady increase over time in the proportion of babies who survive without a major morbidity, including bronchopulmonary dysplasia.”
According to the authors, improvements have come through research-proven practices such as use of antenatal corticosteroid, which has increased from 24 percent in 1993 to 87 percent in 2012. Other studies have shown that strategies to reduce lung injury, such as less aggressive ventilation, decreased use of intubation and increased surfactant use, have led to better outcomes. The reduction in late-onset sepsis could be related to improved hand hygiene, skin care and human milk feeding, as well as uniform practices for catheter placement and discontinuing invasive devices when not needed.
The study also underscored the importance of a joint approach between obstetrical and neonatal intensive care teams.
“The study provides a global overview and level of detail not presented in earlier studies. Findings demonstrate that progress is being made and outcomes of the most immature infants are improving,” the authors wrote. “These findings are valuable in counseling families and developing novel interventions.”
The Neonatal Research Network is part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). UTHealth is one of two network members in the state and the only one in Houston. Data in Houston came from infants born at Children’s Memorial Hermann Hospital and Harris Health’s Lyndon B. Johnson Hospital.
The study, “Trends in Care Practices, Morbidity and Mortality of Extremely Preterm Neonates, 1993-2012,” was funded by the NICHD.
Other researchers at UT Physicians, McGovern Medical School, Children’s Memorial Hermann Hospital, and Harris Health’s Lyndon B. Johnson Hospital who were involved in the study included Jon E. Tyson, M.D., M.P.H.; Georgia E. McDavid, R.N.; Esther G. Akpa, R.N., B.S.N.; Beverly Foley Harris, R.N.; Claudia I. Franco, R.N.C., M.S.N.; Anna E. Lis, R.N., B.S.N.; Sara C. Martin, R.N.; Patricia Ann Orekoya, R.N., B.S.N.; Pattie L. Pierce Tate, R.C.P.; and Maegan C. Simmons, R.N.
— Deborah Mann Lake, Office of Public Affairs