Nonspontaneous late preterm birth: Etiology and outcomes

Objective: We sought to determine the proportion of evidence-based (EB), vs non-EB (NEB) iatrogenic late preterm birth, and to compare corresponding rates of neonatal intensive care unit (NICU) admission. Study Design: We performed a retrospective cohort study. Cases were categorized as EB or NEB. NICU admission was compared between groups in both univariate and multivariate analysis. Results: Of 2693 late preterm deliveries, 32.3% (872/2693) were iatrogenic; 56.7% were delivered for NEB indications. Women with NEB deliveries were older (30.0 vs 28.6 years, P =.001), and more likely to be pregnant with twins (18.8% vs 7.9%, P <.001), have private insurance (80.3% vs 59.0%, P <.001), or have a second complicating factor (27.5% vs 10.1%, P <.001). A total of 56% of EB deliveries resulted in NICU admissions. After controlling for confounders, early gestational age (34 vs 36 weeks: odds ratio, 19.34; 95% confidence interval, 4.2887.5) and mode of delivery (cesarean: odds ratio, 1.88; 95% confidence interval, 1.153.05) were most strongly associated with NICU admission. Conclusion: Over half of nonspontaneous late preterm births were NEB. EB guidelines are needed.