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

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

Prospective, cohort, observational study of late preterm infants (34^0/7-36^6/7 weeks gestational age) and term infants (39^0/7-41^6/7 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 SpO₂) on the oximetry recording on days 2-3 after birth. Data were analyzed by the Student t test and general linear mixed model.

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).

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.