A study recently published in the Journal of the American Medical Association (JAMA) revealed that the survival rate of preterm infants has increased over the last years, while overall the major complications linked to preterm birth have decreased. The study is entitled “Trends in Care Practices, Morbidity, and Mortality of Extremely Preterm Neonates, 1993-2012” and was conducted by researchers at several institutes, hospitals and universities in the United States.
Preterm birth (defined as birth before 37 weeks of gestation) is considered the leading cause of long-term neurological disabilities in children. The Centers for Disease Control and Prevention (CDC) estimates that, in 2012, preterm birth affected more than 450,000 infants, representing 1 in every 9 births. In 2010, 35% of all infant deaths reported were found to be the result of preterm-related conditions. The costs that preterm birth represents for the United States heath care system can reach the value of $26 billion, as was the case in 2005.
In the study, researchers conducted a clinical trial (NCT00063063) to analyze the trends related to care, complications and mortality among extremely preterm neonates in the United States between 1993 and 2012. In total, 34,636 infants considered extremely premature (birth at 22 to 28 weeks of gestation) were evaluated. The infants weighed between 14.1 ounces and 3.3 pounds (401 to 1500 g), and one-fourth of them were from multiple births.
Researchers found that the survival rate increased for infants born at 23 weeks of gestation (27% in 2009 to 33% in 2012) and at 24 weeks (63% in 2009 to 65% in 2012). A small increase in the survival rate was also found for infants born at 25 and 27 weeks gestation, although no changes were observed for infants at 22, 26 and 28 weeks.
Interestingly, the team observed that survival without major complications increased by around 2% per year in infants born at 25 to 28 weeks gestation, whereas in infants at 22 to 24 weeks gestation there was no change in survival without complications, indicating that there is a real need to improve the clinical outcome in the most immature infants. The major complications observed in the study were infection, eye disorders, lung disorders (bronchopulmonary dysplasia), severe bowel disorders (necrotizing enterocolitis) and severe intracranial hemorrhage. As the rate of all major complications declined over time, there was one exception, the rate of bronchopulmonary dysplasia increased for infants born at 26 to 27 weeks of gestation (50% in 2009 to 55% in 2012).
“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,” explained the study’s co-author Dr. Kathleen A. Kennedy from UTHealth Medical School in a press release. “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.”
The research team concluded that over the past 20 years, the survival rate among extremely premature infants has improved, while the major complications associated with the condition have decreased.
“Our findings are cautiously optimistic and demonstrate that progress is being made and outcomes of the most immature preterm infants are improving,” said the study’s lead author Dr. Barbara J. Stoll from Emory University School of Medicine, who will become the dean of UTHealth Medical School on October 1. “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.”
“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.” added Dr. Kennedy.
The team suggests that the improvements observed are the result of practices like the use of antenatal corticosteroid, more adequate care in infants who require ventilation, improved hygiene, human milk feeding, avoidance of invasive devices and proper standard clinical practices such as catheter placement.