RESUMO
INTRODUCTION: The partial oxygen pressure in the air decreases with increasing altitude. This study was designed to compare the pulse oxygen saturation (SpO2) among well full-term neonates at different altitudes during their first 2 h after birth and to establish cutoff values of SpO2 identifying hypoxemia between 30 and 120 min after birth. METHODS: A multisite prospective cohort study was conducted at five participating hospitals from the Chinese High Altitude Neonatal Medicine Alliance. Healthy full-term infants were recruited and divided into four groups based on the altitude. Preductal SpO2 was recorded at 10 min, 10-30 min, and 30-120 min after birth. The 2.5th percentile of the SpO2 distribution range was considered as the cutoff for identifying hypoxemia at each altitude. RESULTS: A total of 727 infants were eligible for analysis. The SpO2 of neonates at different altitudes increased with the time after birth. A higher altitude was associated with lower SpO2, especially Shangri-La (3,509 m) and Yushu (4,360 m). The cutoff SpO2 for identifying hypoxemia during 30-120 min after birth were 94% in Xishuangbanna (847 m), 92% in Kunming (1,983 m), 89% in Shangri-La (3,509 m), and 83% in Yushu (4,360 m). CONCLUSION: An increase in altitude, especially Shangri-La (3,509 m) and Yushu (4,360 m), had a significant impact on SpO2 among healthy full-term neonates during their first 2 h of life. Establishing the cutoff value of SpO2 for identifying hypoxemia during the early postnatal period serves to optimize the oxygen therapy at different altitudes.