Recurrent episodes of apnea occurring in infants born less than 37 weeks of gestation, defined specifically as a pause of breathing for more than 15-20 s, or accompanied by oxygen desaturation (SpO2 not more than 80% for at least 4 s) and bradycardia (heart rate less than 2/3 of baseline for at least 4 s), in infants born less than 37 weeks of gestation. [from
HPO]