Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.

Objective: There is a relative paucity of data regarding neonatal outcomes in the late preterm cohort (34 to 36 6/7 weeks). This study sought to assess differences in adverse outcomes between infants delivering 32 to 33 6/7, 34 to 36 6/7 weeks, and 37 weeks or later.

Study Design: Data were collected as part of a retrospective cohort study of preterm labor patients (2002-2005). Patients delivering 32 weeks or later were included (n = 264). The incidence of adverse outcomes was assessed. Significant associations between outcomes and gestational age at delivery were determined using chi(2) analyses and Poisson regression modeled cumulative incidence and controlled for confounders.

Results: Late preterm infants have increased risk of adverse outcomes, compared with term infants. Controlling for confounders, there was a 23% decrease in adverse outcomes with each week of advancing gestational age between 32 and 39 completed weeks (relative risk 0.77, P < .001, 95% confidence interval, 0.71-0.84).

Conclusion: Further investigation regarding obstetrical management and long-term outcomes for this cohort is warranted.