Abstract:

Objective: To investigate the postpartum factors of vaginal birth after cesarean(VBAC). Methods: From January 2016 to November 2021, the pregnant women who underwent the trial of labor after cesarean section (TOLAC) in The Fourth Affiliated Hospital of Hebei Medical University were retrospectively analyzed. All included cases were the first vaginal delivery after a single cesarean section. The medical records included: maternal age, fetal head position during labor, latent period, whether use oxytocin to strengthen contractions during labor, fetal head position during active period (4-5 cm), and fetal position. The influencing factors of VBAC were analyzed by the univariate and multivariate logistic regression. Results: ①There were 319 pregnant women tried vaginal delivery, of which 236 had a final vaginal delivery, with a VBAC rate of 74.0%. ②The univariate analysis showed that the fetal head in the active phase (4-5 cm) was located at the level of the ischial spine or below (85.3% vs. 59.9%, OR=3.895, 95%CI: 2.282-6.647), and the fetal position is anterior occipital (83.6% vs. 62.8%, OR=3.020, 95%CI: 1.787-5.104) had higher successful rate of TOLAC. The success rate of TOLAC was lower in women who needed oxytocin strengthens contractions during labor (61.2% vs. 77.4%, OR=0.461, 95%CI: 0.260-0.818). There were no significant differences in the maternal age, fetal head position at delivery and latent period between the two groups (P>0.05). ③Multivariate analysis showed that oxytocin use during labor (OR=0.502, 95%CI: 0.267-0.943), fetal head at or below the level of ischial spine during active phase (OR=3.467, 95%CI: 1.990-6.042), fetal position at the anterior occipital (OR=2.633, 95%CI: 1.515-4.575) were independent influencing factors of VBAC. Conclusions: For pregnant women who underwent TOLAC, the maternal and fetal situation and labor progress should be closely monitored when the labor progresses to the beginning of active phase, the fetal head is still above the level of ischial spine, and fetal position is occipital/posterior, or oxytocin is used to strengthen the contractions during labor. If necessary, the surgical indications for cesarean section should be relaxed to ensure the safety of maternal and fetal.

Key words: Vaginal birth after cesarean, Root cause analysis, Oxytocin, Abnormal fetal positions, Trial of labor after cesarean section, During delivery