Improved Survival Seen For Premature Infants

Improved Survival Seen For Premature Infants
–Better maternal care practices credited with better outcomes

While overall survival rates for premature infants remained relatively stable, survival rates to discharge and survival rates without major morbidities have exhibited slight increases over time, according to a large prospective, longitudinal study of data from extremely premature infants over the last 20 years.

Barbara J. Stoll, MD, of Emory University in Atlanta, and colleagues found that overall survival to discharge for infants at 23 and 24 weeks gestation increased slightly from 2009 to 2012 (27% to 33%, P<0.001 and 63% to 65%, P<0.001, respectively), with smaller increases reported for infants born at 25 and 27 weeks gestation.

In addition, the portion of infants surviving without any major morbidity increased from 43% in 1993 to almost 60% (59%) in 2012 (P<0.001), they wrote in the Journal of the American Medical Association.

There was no change in survival rates for infants born at 22, 26, or 28 weeks, though researchers noted slight year-to-year increases for infants born from 25 to 28 weeks gestation (approximately 2% per year). Not surprisingly, trends in overall survival and survival without major morbidity varied by gestational age.

Stoll told MedPage Today she was not exactly surprised by the findings, but was pleased to see these steady increases in survival rates.

“We’re cautiously optimistic that outcomes are improving, that a number of morbidities have decreased,” she said. “Although this study doesn’t report long-term outcomes, we hope that the improvements in survival without hospital complications will result in an improvement in long-term outcomes.”

Along with improved survival rates, the authors observed improvements in maternal care practices. The most significant trend was the use of antenatal steroids, which increased dramatically from 1993 to 1996 (24% to 74%, P<0.001) with smaller increases up through 2012 (87%). Other statistically significant trends included:

  • Antenatal antibiotic use: 44% in 2993 vs 73% in 2012, P<0.001
  • Cesarean deliveries: 44% in 1993 vs 62% in 2005, P<0.001
  • Delivery room tracheal intubation: 80% in 1993 vs 65% in 2012, P<0.001

There were increases in the use of surfactant (60% in 1993 vs 78% in 2003), though those were not statistically significant. Use of resuscitation drugs and chest compression also declined over time.

Stoll added that the increase in use of antenatal steroids, C-section delivery, and maternal antibiotics all suggest more willingness on the part of obstetricians and parents to provide active management for pregnancy and infants that are extremely preterm, and that maternal and neonatal interventions with an evidence base to improve outcomes are increasingly being followed.

Overall, other major neonatal morbidities, late-onset sepsis, intracranial hemorrhage, and retinopathy of prematurity exhibited slight declines or remained relatively stable, and these declines were associated with increasing gestational age. However, there was an increase in the diagnosis of bronchopulmonary dysplasia (BPD). Rates of diagnosis actually rose from 32% in 1993 to 40% in 2008. From 2009 to 2012, there were statistically significant increases for infants born at 26 weeks (50% to 55%,P<0.001) and 27 weeks (33% to 40%, P=0.007).

While not involved with this study, Timmy Ho, MD, of Beth Israel Deaconess Medical Center in Boston said he too was not surprised by these findings. He added that while neonatologists all likely know that rates of bronchopulmonary dysplasia are increasing, it’s definitely discouraging to see such a large dataset show the same trends, and suggested future research on the reasons for the increase might be necessary.

“While the authors surmise that increased active resuscitation, intensive care, and increased survival, especially for the most immature infants, may be contributing to the slowly rising rates of bronchopulmonary dysplasia, this study leaves those questions largely unanswered,” Ho told MedPage Today via e-mail. “Our work and how it affects the long term respiratory and developmental outcomes of our patients requires further study as to why, despite all of our advances in more gentle methods of ventilating patients, rates of bronchopulmonary dysplasia continue to rise.”

Researchers examined data from the National Institute of Child Health Neonatal Research Network (NRN) which included infants from 22 to 28 weeks gestation, with a birth weight of 401 to 1,500 g and born at 26 network centers from 1993 to 2012. Regression models were adjusted for study center, race/ethnicity, gestational age, birth weight for gestational age, and sex. The authors note that findings used to be reported by birth weight, but in 2010, they began reporting by gestational age.

Limitations to the study include that the NRN cohort is hospital-based as opposed to population-based, and thus not representative of the entire U.S. preterm population. In addition, infants who died within the first 12 hours are included in the study, but not in the analyses of morbidities. This data only follows infants to hospital discharge, as opposed to including longer-term outcomes.

Stoll said that it was her hope that these data would add to the information base that help parents and physicians in their complex decision-making process in the care of extremely preterm infants.

“We hope the data will guide clinicians and scientists to focus their attention in areas in OB and neonatology that still need improvement,” she concluded.


Reviewed by F. Perry Wilson, MD, MSCE
Assistant Professor, Section of Nephrology, Yale School of Medicine

Primary Source
Journal of the American Medical Association
Source Reference: Stoll BJ, et al "Trends in care practices, morbidity and moratlity 
of extremely preterm neonates, 1993-2012" JAMA 2015; DOI: 10.1001/jama.2015.10244.


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