Biomarkers of Maternal and Neonatal Oxidative and Nitrosative Stress During Delivery: An Exploratory Pilot Study on Maternal–Neonatal Adaptation to Stress

Background/Objectives: Perinatal oxidative and nitrosative stress may contribute to maternal–neonatal adaptation during delivery. This pilot study evaluated pathway-specific oxidative and nitrosative stress markers from blood samples in paired mother–newborn dyads and explored their associations with delivery-related variables, maternal smoking habits and neonatal clinical state. Methods: The study included 74 mother–newborn dyads, yielding 148 paired maternal and neonatal investigations. Biomarkers included plasma nitrite, nitrate, malondialdehyde, and reduced and oxidized glutathione. Composite pathway-specific indices were calculated: an Oxidative Stress Index (OSI) and a Nitrosative Stress Index (NSI). Results: Paired testing showed that OSI was significantly higher in the maternal compartment compared to the neonatal compartment (p < 0.001), while NSI showed no significant difference (p = 0.594). Maternal and neonatal indices showed positive monotonic correlations (OSI Spearman’s rho = 0.608, p < 0.001; NSI Spearman’s rho = 0.275, p = 0.018). Following false discovery-rate correction (FDR) across the exploratory inferential analysis, no raw or composite biomarkers showed statistically significant differences. Conclusions: This study indicates that while maternal and neonatal oxidative indices are monotonically correlated, their absolute concentrations shift significantly across compartments, highlighting the need to treat these indices as strictly exploratory, hypothesis-generating metrics.