Neonatal Acidemia and Hypoxia

This study aims to improve understanding of how fetuses respond to oxygen deprivation during labor by re-evaluating cardiotocography (CTG) recordings using a physiology-based interpretation approach and comparing these findings with umbilical cord blood gas measurements at birth, including eucapnic pH assessment. The study will include term pregnancies and combines retrospective data analysis with prospective enrollment. Researchers will investigate whether physiology-based CTG interpretation can better identify signs of fetal compromise and whether eucapnic pH may improve the distinction between respiratory and metabolic acidosis. Findings may contribute to improving fetal monitoring strategies and the assessment of newborn condition at birth.

Severe neonatal acidosis is an identified risk factor for neonatal encephalopathies and severe neurological sequelae such as cerebral palsy. While intrapartum origin of such deterioration is rare (approximately 20% of adverse outcomes in term infants), screening for hypoxia that can lead to the development of severe acidosis remains inadequate. This results in both delays in diagnosis and/or intervention, and a parallel increase in obstetric interventions (cesarean sections and operative vaginal deliveries) sometimes performed with inappropriate indications, thus contributing to unnecessary maternal and neonatal comorbidities. Difficulties in analyzing fetal heart rate (FHR) patterns are identified as an independent risk factor, particularly due to significant inter- and intra-observer variability, in an examination that is nevertheless central to assessing fetal well-being during labor. An FHR analysis based on a thorough understanding of the physiology of fetal adaptation to hypoxia could allow for better recognition of situations where fetal compensation for hypoxic stress is no longer possible, when adaptive mechanisms are exhausted. Given that FHR interpretation errors are implicated in 35 to 50% of adverse neonatal outcomes (peripartum death, early neonatal death, or irreversible brain damage), the preventability of these traumatic complications for families is systematically called into question. Furthermore, recent data suggest that defining hypoxia profiles associated with tracing characteristics would allow for more accurate identification of these situations, and for improved use of intervention in a more appropriate manner in terms of time and resources, in an attempt to reduce the incidence of neonatal complications of hypoxic origin involved in the development of severe neurological sequelae.