Neonatal acidemia with trial of labor among parturients with prior cesarean delivery: a case-control study

To determine the risk factors for neonatal acidemia with trial of labor among parturients with a prior cesarean delivery.

From a prospectively collected database on all parturients attempting a trial of labor, newborns with umbilical arterial pH < 7.15 were selected as cases and the controls (1:4) were the next four patients who delivered nonacidotic (pH > or = 7.15) neonates. Exclusion criteria were no prior cesarean delivery, anomalous fetus, and nonavailability of umbilical arterial blood gas analysis. Student's t-test, chi2, and Fisher's exact tests were utilized and odds ratio (OR) and 95% confidence intervals (CI) were calculated. P < 0.05 was considered significant.

The frequency of neonatal acidemia among patients undergoing trial of labor was 12% (28/234). The cases and controls (n = 112) were similar (P > 0.05) with regards to maternal age, frequency of more than one prior cesarean delivery (11% vs. 8%), gestational age, cervical exam on admission (3.0 +/- 1.5 vs. 3.4 +/- 1.7 cm), usage of oxytocin, and duration of first or second stage of labor. The mean birthweight was significantly higher among acidotic (3,758 +/- 670 g) than nonacidotic (3,470 +/- 545 g; P = 0.018) newborns. Compared to the controls, the cases had a significantly higher frequency of unsuccessful trial of labor (19% vs. 50%; OR: 4.09; 95% CI: 1.70, 9.82) and separation of the uterine scar (0.8% vs. 14%; OR: 18.50; 95% CI: 1.98, 173.05).

Acidotic newborns with trial of labor tend to be heavier. Parturients have a failed attempt at vaginal birth after cesarean, and have separation of the uterine scar during labor.