While the improvement in survival rates of extremely preterm infants might seem insignificant at first glance, a University of Rochester Medical Center researcher says that increase is anything but small.
“We now have the ability to tell parents with children just early in (the process of) gestation, ‘We have treatment we can offer you,’ unlike the previous comment, ‘There’s nothing we can do,’” says Carl D’Angio M.D., chief of the division of neonatology at URMC. “Being able to say that to parents, that’s the reason we do what we do.”
Preterm birth, when a baby is born before 37 weeks of pregnancy, is one of the leading causes of infant mortality. The Centers for Disease Control and Prevention says infant mortality rate is a key marker of the overall health of society. In 2020, preterm birth affected one of every 10 infants born in the United States, CDC states.
D’Angio co-authored a paper that examined survival outcomes of infants born between 22 and 28 weeks at the 19 academic medical centers in the NIH-funded Neonatal Research Network. The study found that the survival rates had increased from approximately 76 percent in the previous 2008-12 study to 78 percent from 2013 to 2018.
“This is where we get into the idea of statistically significant versus clinically significant. Where there was the most growth was (among) the most vulnerable of this already vulnerable population,” he says, referring to actively treated infants who are classified as extremely premature.
Among actively treated infants at 22 weeks, survival was 30 percent, while at 23 weeks, it was 55.8 percent. This is a considerably higher rate of survival than in the previous study where survival to discharge was 7 percent for 22-week-old infants and 32 percent for 23-week-old infants.
“It is mind-boggling we have gotten this far. When I first started, at best, the rate we could say for infants born at 24 weeks was 50 percent,” says D’Angio, a 24-year-veteran of the public health field. “Nationwide, it’s now 70 percent. When you look at our (Neonatal Research Network) centers, it’s more like 80 percent.”
Infants born this early often face issues related to the underdevelopment of organ systems, most notably the respiratory and digestive system. D’Angio speculates that the survivability increase is related to improvements in treating these areas.
For example, surfactant, a compound that helps the lung alveoli (air sacs) open, is typically produced beginning at 24 to 28 weeks gestation. It takes approximately seven more weeks for babies to produce adequate amounts of surfactant to keep the alveoli from collapsing.
Since the 2008-12 study, putting preterm infants on ventilators for this issue is less common. Doctors can now give surfactant to infants, which, while not fixing the respiratory underdevelopment, can keep them alive long enough for their own systems to develop.
“It takes a while for the body to wake up and say, ‘We’re out in the air, we need to make surfactant,’” D’Angio says.
In addition, many academic medical centers, like those in the study, have switched from giving preterm infants baby formula to human milk. Researchers think this better develops the infant’s digestive system and can also avoid intestinal diseases.
These findings correlate to the outcomes nationwide. Over the past two decades, the U.S. has seen a decrease in preterm infant births, according to the years tracked by the World Health Organization. Out of the 88 regions surveyed by the WHO, the U.S. had the 10th-highest rate of preterm births with nearly 12 percent, or one in nine. This rate fell to 9.6 percent (29th highest) in 2014, the most recent year studied by the WHO.
However, when it comes to infant mortality as a whole, the U.S. lags other industrialized countries. According to the latest available data from the Organization for Economic Co-operation and Development, the U.S. had 5.7 infant deaths per 1000 births in 2018, ranking 11th highest out of 44 countries.
Differences between the U.S. and infant mortality rates in other developed countries exist in part because of different population sizes and the way the public health system is set up, D’Angio says.
“In other countries, you can have a more direct and aggressive treatment plan in place in a wider amount of centers,” D’Angio says, noting that the study he participated in focused on academic medical centers, which generally have better practices.
In addition to studying survival outcomes, the study assessed the health of severely preterm infants after two years, including effects such as neurodevelopment, cerebral palsy, vision, hearing, rehospitalizations, and need for assistive devices. Nearly 49 percent had no or only mild neurodevelopmental impairment, about 29 percent had moderate neurodevelopmental impairment and roughly 21 percent had severe neurodevelopmental impairment.
Still, the study overall offers a reason for hope, D’Angio says, and that looking at statistics without nuance is missing part of the picture.
“We have improved our level of care and we can show it with this data from 2013 to 2018,” he says. “And I can tell we’re doing better already and that, in five years, when we update the study again, it will show we improved our level of care again.”
Jacob Schermerhorn is a Rochester Beacon contributing writer. The Beacon welcomes comments from readers who adhere to our comment policy including use of their full, real name.