Highland populations suffer from significant infant mortality due to chronic ambient hypoxia, which increases the risk of congenital heart disease (CHD) and neonatal pulmonary hypertension. Neither the prevalence of these conditions nor the effectiveness of neonatal cardiac screening to identify CHD or pulmonary hypertension among neonates born at altitudes >
4000 m in Bolivia has been reported. In a study of 1033 newborns in El Alto, Bolivia (4510 m), we determined the prevalence of CHD and prolonged postnatal adaptation. We also tested the accuracy of a neonatal cardiac screening tool in identifying infants with/without these conditions. Finally, diagnoses were contrasted between offspring born to parents of lowland versus highland origin. CHD was found in 54 neonates (5.2%), with the most common diagnoses being patent ductus arteriosus and atrial septal defect. Pulmonary hypertension without CHD was observed in 64 neonates (6.8%), with seven cases of persistent pulmonary hypertension of the newborn (PPHN). The neonatal cardiac screening tool showed a sensitivity of 45% and specificity of 99% for CHD, and 35% sensitivity and 92% specificity for prolonged pulmonary adaptation. Offspring of highland-origin women tended to have increased CHD risk, while those from lower altitudes were predisposed to prolonged postnatal adaptation and PPHN
paternal altitude of origin had no statistic significance but showed same tendency. The high prevalence of relevant CHD and prolonged pulmonary adaptation in neonates born >
4000 m in Bolivia likely contributes to the high infant mortality rates observed. The poor sensitivity of the pilot neonatal cardiac screening instrument underscores the need to develop evidence-based tools optimized for use in low-resource, high-altitude settings.