Association of Intrapartum Cardiotocography Findings with Umbilical Arterial Blood Gas Parameters and Neonatal...

Objectives: To investigate the relationship between intrapartum cardiotocography (CTG) findings and neonatal outcomes by evaluating the association between CTG tracings, umbilical cord blood gas parameters, and APGAR scores, and to assess the diagnostic performance of CTG in identifying fetuses at risk of neonatal acidemia. Methods: This prospective study included women who delivered at a tertiary teaching hospital between January 2017 and January 2018. Of 1100 women initially screened, 596 met the inclusion criteria and were analyzed. Among them, 162 underwent operative delivery for non-reassuring fetal status (NRFS), while 434 served as controls. Demographic, obstetric, and neonatal characteristics were compared. Multivariable logistic regression was performed to explore factors associated with umbilical arterial pH < 7.20. Results: Mean umbilical arterial pH was significantly lower in the NRFS group than in controls (7.30 ± 0.08 vs. 7.32 ± 0.07, p < 0.05). Umbilical arterial pH differed significantly across NICHD fetal heart rate categories, with the highest values observed in Category I tracings. Twenty-eight neonates (4.7%) had an umbilical arterial pH < 7.20. CTG-based identification of NRFS predicted umbilical arterial pH < 7.20 with a sensitivity of 42.9%, specificity of 73.6%, positive predictive value of 7.4%, and negative predictive value of 96.3%. In multivariable analysis, pregestational diabetes mellitus and preeclampsia were independently associated with umbilical arterial pH < 7.20. Conclusions: Although CTG remains an essential tool for intrapartum fetal surveillance, its low positive predictive value indicates that many fetuses classified as having NRFS do not have biochemical evidence of acidemia. CTG findings should therefore be interpreted together with the overall clinical context, including maternal risk factors such as pregestational diabetes mellitus and preeclampsia, rather than being used in isolation to guide intrapartum management.