High-Altitude Hypoxia, Fetal Growth Restriction, and Early Neonatal Outcomes: A Two-Center Comparative Study

High altitude is associated with reduced barometric pressure and lower oxygen availability, which may impair fetoplacental oxygen transfer and adversely affect fetal growth and neonatal adaptation. This study compared birth weight, maternal oxygenation parameters, and early neonatal outcomes between two centers located at 1800 m and 2500 m above sea level in Eastern Türkiye.In this comparative cross-sectional study, 540 mother–infant pairs were evaluated, including 270 deliveries from Ardahan (1800 m) and 270 from Göle (2500 m). Data were obtained from retrospectively reviewed hospitals from 2018 year. Maternal partial pressure of oxygen (PaO₂), oxygen saturation (SaO₂), hemoglobin, lactate, gestational age, mode of delivery, birth weight, small-for-gestational-age (SGA) status, and neonatal intensive care unit (NICU) admission were compared between centers. Continuous variables were analyzed using independent-sample t tests and analysis of variance, whereas categorical variables were compared using chi-square tests. Additional analyses included analysis of covariance, multivariable linear regression, logistic regression for SGA and NICU admission, interaction analysis, receiver operating characteristic analysis, and effect size estimation. Compared with the 1800 m group, pregnancies at 2500 m were associated with lower mean birth weight (2315 g vs 3396 g), lower maternal PaO₂ and SaO₂, and higher hemoglobin and lactate levels (all p