More Extremely Preterm Infants Surviving, Fewer Complications

Troy Brown, RN

September 09, 2015

Complications have decreased and survival has improved for extremely preterm infants born at US academic centers during the last 20 years, according to a new study published in the September 8 issue of JAMA.

"[C]hanges in maternal and infant care practices and modest reductions in several morbidities were observed, although bronchopulmonary dysplasia increased," Barbara J. Stoll, MD, from the Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta in Georgia, and colleagues report.

"Survival increased most markedly for infants born at 23 and 24 weeks' gestation and survival without major morbidity increased for infants aged 25 to 28 weeks. These findings may be valuable in counseling families and developing novel interventions," they add.

The authors reviewed 20-year trends in maternal/neonatal care, complications, and deaths among extremely preterm infants born at 26 Neonatal Research Network Centers between 1993 and 2012.

The researchers analyzed data from a prospective registry of 34,636 infants of 22 to 28 weeks' gestation, weighing 401 to 1500 g at birth.

The study's main outcomes were maternal/neonatal care, morbidities, and survival. The primary morbidities reported for infants who lived for more than 12 hours were severe necrotizing enterocolitis, infection, bronchopulmonary dysplasia, severe intracranial hemorrhage, cystic periventricular leukomalacia, and/or severe retinopathy of prematurity.

The investigators used regression models to assess yearly changes and adjusted for study center, race/ethnicity, gestational age, birth weight for gestational age, and sex.

Antenatal corticosteroid use increased from 1993 to 2012, going from 24% (348 of 1431 infants) to 87% (1674 of 1919 infants; P < .001). The number of cesarean deliveries also increased, going from 44% (625 of 1431 births) in 1993 to 64% in 2012 (1227 of 1921; P < .001).

Intubation of infants in the delivery room decreased from 80% (1144 of 1433 infants) in 1993 to 65% (1253 of 1922 infants) in 2012 (P < .001). "After increasing in the 1990s, postnatal steroid use declined to 8% (141 of 1757 infants) in 2004 (P < .001), with no significant change thereafter," the authors note.

Most infants were ventilated, but use of continuous positive airway pressure without ventilation rose from 7% (120 of 1666 infants) in 2002 to 11% (190 of 1756 infants) in 2012 (P < .001).

Late-onset sepsis rates failed to improve from 1993 to 2004, but fell between 2005 and 2012 for infants at each gestational age (median, 26 weeks), going from 37% (109 of 296) to 27% (85 of 320; adjusted relative risk [RR], 0.93; 95% confidence interval [CI], 0.92 - 0.94).

Other morbidity rates declined, but bronchopulmonary dysplasia rose between 2009 and 2012 for infants at 26 to 27 weeks' gestation, going from 50% (130 of 258) to 55% (164 of 297; P < .001).

Survival Rates

Between 2009 and 2012, survival increased for infants at 23 weeks' gestation, going from 27% (41 of 152) to 33% (50 of 150; adjusted RR, 1.09; 95% CI, 1.05 - 1.14). Survival rates also increased for infants at 24 weeks' gestation, going from 63% (156 of 248) to 65% (174 of 269; adjusted RR, 1.05; 95% CI, 1.03 - 1.07). Smaller relative increases were seen for infants at 25 and 27 weeks' gestation, and no change for infants was seen at 22, 26, and 28 weeks' gestation.

Survival with no major morbidity rose about 2% per year for babies at 25 to 28 weeks' gestation, and there was no change for infants at 22 to 24 weeks' gestation.

"Perhaps not seeing substantial changes in survival in the more mature infants in this cohort is not surprising; these infants are no longer at high risk of dying," Roger F. Soll, MD, from the University of Vermont College of Medicine, Vermont Oxford Network, and the University of Vermont Medical Center, Burlington, writes in an accompanying editorial. "What is heartening is the improvement in survival without morbidity observed among infants at 27 and 28 weeks' gestation (27 weeks: 35% in 1993 to 50% in 2012 among infants surviving to discharge; 28 weeks: 43% to 59%). The unfortunate corollary to this finding is that although survival improved in the least-mature infants, no improvement in survival without morbidity was seen in infants who were 22 to 24 weeks' gestation."

With the improved outcomes for infants at 23 to 24 weeks' gestation, neonatologists and other clinicians have started to question the lower limits of viability and expected resuscitation at gestational ages younger than 23 weeks, writes Dr Soll. Outcomes were better in hospitals where more aggressive treatment was given.

"However, even with intervention, rates of mortality and morbidity were high with only 9% of these infants surviving without moderate or severe impairment, calling into question whether this should be the next important frontier for neonatal intensive care," he adds.

"Although the neonatal-perinatal medicine community can be proud of the progress made, an additional commitment must be made to further improvements in the decades to come."

The authors have disclosed no relevant financial relationships. Dr Soll reports receipt of personal fees (serving as president and member of the board of directors) from the Vermont Oxford Network outside the submitted work.

JAMA. 2015;314:1007-1008, 1039-1051. Article abstract, Editorial extract

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