Intermittent Hypoxemia in Infants Born Late Preterm: A Prospective Cohort Observational Study

Objective: To determine if late preterm infants are at increased risk of intermittent hypoxemic events compared with term infants.

Study Design: Prospective, cohort, observational study of late preterm infants (34-36 weeks gestational age) and term infants (39-41 weeks gestational age). Overnight pulse oximetry recordings were performed on days 2-3 after birth, at term equivalent age, and at 45 weeks postmenstrual age. The primary outcome was the frequency of intermittent hypoxemic events per hour (desaturation ≥10% below the preceding baseline SpO) on the oximetry recording on days 2-3 after birth. Data were analyzed by the Student t test and general linear mixed model.

Results: Eighty-five infants were enrolled (late preterm n = 43; term infants n = 42). On days 2-3 after birth, late preterm infants had more intermittent hypoxemic events than term infants (events per hour, mean ± standard error of the mean, 2.5 ± 1.2 vs 1.0 ± 1.2; P < .0001). On mixed model analysis, late preterm infants had a higher frequency of intermittent hypoxemic events at term equivalent age, which decreased to a similar frequency as in term infants by 45 weeks postmenstrual age (events per hour; term equivalent age, late preterm: least squares mean, 3.7 [95% CI, 2.7-5.1] vs term: least squares mean, 1.7 [95% CI, 1.2-2.3]; 45 weeks postmenstrual age, late preterm: least squares mean, 1.5 [95% CI, 1.1-2.1] vs term: least squares mean, 1.9 [95% CI, 1.4-2.6]; P < .0005).

Conclusions: Late preterm infants are at greater risk of intermittent hypoxemia than term infants soon after birth. We speculate that preventing intermittent hypoxemia in late preterm infants may improve neurodevelopmental outcomes.