Longitudinal assessment of hemoglobin oxygen saturation in preterm and term infants in the first six months of life

Objective: To report longitudinal home recordings of hemoglobin O ₂ saturation by pulse oximetry (Spo₂) during unperturbed sleep in preterm and term infants. Study design: We recorded continuous pulse oximetry during the first 3 minutes of each hour of monitor use (nonevent epochs) for 103 preterm infants born at <1750 g and ≤34 weeks postmenstrual age (PMA), and 99 healthy term infants. Results: Median baseline Spo₂ was approximately 98% for both the preterm and term groups. Episodes of intermittent hypoxemia occurred in 74% of preterm and 62% of term infants. Among infants with intermittent hypoxemia, the number of seconds/hour of monitoring <90% Spo₂ was initially significantly greater in the preterm than the term group and declined with age at a similar rate in both groups. The 75^th to 95^th percentiles for seconds/hour of Spo₂ <90% in preterm infants were highest at 36 weeks PMA and progressively decreased until 44 weeks PMA, after which time they did not differ from term infants. Conclusions: Clinically inapparent intermittent hypoxemia occurs in epochs unperturbed by and temporally unrelated to apnea or bradycardia events, especially in preterm infants at 36 to 44 weeks PMA.