Fetal Acidosis from Obstetric Interventions During the First Vaginal Delivery

Abstract

Objective: The aim of this study was to analyze the blood gas values of umbilical cord blood in newborns of first vaginal deliveries with or without obstetric interventions. Materials and Methods: In a prospective descriptive study conducted during the 6-month period from August 2003 through February 2004 at a university hospital, we analyzed the umbilical cord blood gas results of 80 term newborns delivered vaginally from healthy nulliparous women. Multivariate logistic analysis was used to evaluate the associations between fetal acidosis (pH < 7.20) and any obstetric interventions. Results: The mean of umbilical cord blood arterial pH was 7.26 (standard deviation, 0.072). After controlling for the confounding factors with multivariate logistic regression, fetal acidosis (pH < 7.20) was found to be significantly associated with oxytocin augmentation (odds ratio [OR], 16.48; 95% confidence interval [CI], 1.21–226.1) and vacuum extraction (OR, 10.76; 95% CI, 1.025–112.9). In contrast, there was no significant relationship between fetal acidosis with episiotomy (OR, 1.096; 95% CI, 0.07–16.6) or epidural anesthesia (OR, 0.074; 95% CI, 0.003–2.09). Conclusion: Oxytocin augmentation and vacuum extraction were significantly related to low cord arterial pH values (pH < 7.20), but there were no adverse effects to the newborns of first vaginal deliveries.

Keywords

• fetal acidosis
• first vaginal delivery
• low cord arterial pH
• obstetric interventions
• umbilical blood gas analysis