Adverse Outcomes in Late-Preterm Infants

RDS12% at 33–34 wk, 2% at 35–36 wk, and 0.11% at term27; 30.8% at 35–36 0/7 wk27
TTN11.6% at 33–34 wk, 5% at 35–36 wk, and 0.7% at term27, 28
Pulmonary infection0.16% at 35–36 wk and 0.08% at term27, 28
Unspecified Respiratory failure3% at 33–34 wk, 2.48% at 35–36 wk, and 0.24% at term27, 28
Recurrent apnea4%–5% at 34–36 wk vs 0% at term34
Temperature instability10% at 35–36 wk vs 0% at term2
Jaundice as cause for discharge delay16.3% at 35–36 wk vs 0.03% at term2
Bilirubin-induced brain injuryLate-preterm infants represent a large fraction of infants in kernicterus registries54
Hypoglycemia18% at 35–36 wk vs 4% at term2
Clinical problem with ≥1 diagnoses77.8% at 35–36 wk vs 45.3% at term2
Rehospitalization for all causes5.3%–9.6% for infants at 33–37 wk vs 3.6%–4.4% at 38–48 wk7
Rehospitalization for neonatal dehydrationOdds ratio at gestational age of <39 vs >39 wk: 2.0 (95% confidence interval: 1.2–3.5)8
BrainIt is estimated that the brain size at 34–35 wk of gestation is ∼60% of term40; in late-preterm infant autopsies, significant periventricular leukomalacia has been found40, 41
MortalityDeath from all causes for births at 34–36 vs ≥37 wk; early neonatal death relative risks: 5.2; late neonatal death: 2.9; postneonatal death: 2.0; total infant mortality: 2.5; in Canada, the respective rates for relative risk are 7.9, 3.6, 3.0, and 4.5; the 95% confidence intervals ranged from 1.9 to 9.2 for data from both the United States and Canada12
Feeding difficultiesDifficulty in initiating and continuing breastfeeding; difficulty in coordinating suck and swallow9, 10, 37
Long-term behavioral problemsHigher incidence of learning and behavioral problems at school age49, 50
  • Includes topics that were presented at the workshop (not intended to be a comprehensive review of the literature). For additional information on specific data, please refer to the articles cited here and in the text.