Duration of first vaginal birth following cesarean: Is stage of labor at previous cesarean a factor?

The continuum of a prolonged labor and a second stage cesarean delivery

OBJECTIVE

To investigate the association of the timing of primary cesarean delivery with the progress of labor and the operative delivery rate at the subsequent successful trial of labor.

METHODS

A retrospective study of women with a primary cesarean and subsequent term cephalic vaginal delivery in two medical centers. Cesarean deliveries were classified as planned, intrapartum first stage or intrapartum second stage. The second stage duration and the operative delivery rate, adjusted to epidural analgesia and oxytocin use, were compared between the groups. χ² and Kruskal-Wallis tests were used for analysis of categorical and continuous variables, respectively.

RESULTS

The study population included 1166 women. The second stage of labor was longer when the previous cesarean delivery occurred during the second stage compared to planned or first stage (1.7 h vs 1.3 h vs 1.3 h, p = 0.005). The proportion of operative deliveries was greater among women with previous cesarean in the second stage of labor (39.6%), compared to planned (26.9%) or first stage (28.8%), p = 0.006.

CONCLUSION

Cesarean delivery at the second stage of labor is associated with a longer second stage and an increased operative delivery rate at the subsequent vaginal birth. Our findings attest to the delicate passenger-passage relations that can exist in some parent-couples.

Fetal Head Station at Second-Stage Dystocia and Subsequent Trial of Labor After Cesarean Delivery Success Rate

OBJECTIVE

To investigate whether fetal head station at the index cesarean delivery is associated with a subsequent trial of labor success rate among primiparous women.

METHODS

A retrospective cohort study conducted at two tertiary medical centers included all primiparous women with subsequent delivery after cesarean delivery for second-stage dystocia during 2009-2019, identified from the electronic medical record databases. Univariate and multivariate analyses were performed to assess the factors associated with successful trial of labor after cesarean (TOLAC) (primary outcome). Additionally, all women with failed TOLAC were matched one-to-one to women with successful TOLAC, according to factors identified in the univariate analysis.

RESULTS

Of 481 primiparous women with prior cesarean delivery for second-stage dystocia, 64.4% (n=310) attempted TOLAC, and 222 (71.6%) successfully delivered vaginally. The rate of successful TOLAC was significantly higher in those with fetal head station below the ischial spines at the index cesarean delivery, as compared with those with higher head station (79.0% vs 60.5%, odds ratio [OR] 2.46, 95% CI 1.49-4.08). The proportion of neonates weighing more than 3,500 g in the subsequent delivery was lower in those with successful TOLAC compared with failed TOLAC (29.7% vs 43.2%, OR 0.56, 95% CI 0.33-0.93). In a multivariable analysis, lower fetal head station at the index cesarean delivery was the only independent factor associated with TOLAC success (adjusted OR 2.38, 95% CI 1.43-3.96). Matching all women with failed TOLAC one-to-one to women with successful TOLAC, according to birth weight and second-stage duration at the subsequent delivery, lower fetal head station at the index cesarean delivery remained the only factor associated with successful TOLAC.

CONCLUSION

Lower fetal head station at the index cesarean delivery for second-stage dystocia was independently associated with a higher vaginal birth after cesarean rate, with an overall acceptable success rate. These findings should improve patient counseling and reassure those who wish to deliver vaginally after prior second-stage arrest.

Number of prior vaginal deliveries and trial of labor after cesarean success

OBJECTIVE

Prior vaginal delivery (VD), including vaginal birth after cesarean (VBAC), is one of the greatest predictors of successful trial of labor after cesarean (TOLAC) and uterine rupture. We aimed to evaluate VBAC and uterine rupture rates associated with TOLAC in women with VD prior to cesarean delivery (CD) or with prior VBAC, and the cumulative effect of the number of prior VD's.

STUDY DESIGN

This retrospective study included women having TOLAC between 2005-2019. The study compared the caesarean and uterine rupture rates of TOLAC in women with only prior VD as compared to women with only prior VBAC. Comparison analysis was performed by univariate analysis and followed by adjusted multiple logistic regression models. Receiver operating characteristic (ROC) and decision tree analyses (chi-square automatic interaction detection algorithm) was conducted to evaluate the influence of the number of prior VD's on the likelihood of successful TOLAC.

RESULTS

Overall, 9,038 women met the inclusion criteria. Women with prior VBAC and prior VD showed significantly higher rates of successful VBAC compared to those with no prior VD or prior VBAC (96 % and 86 % vs 76 %; p < 0.01). However, women with prior VBAC but not women with prior VD showed significantly lower rates of uterine rupture compare to women with no prior VD or VBAC (0.1 % vs 0.6 % and 0.6 %; p < 0.01). The prevented fraction of TOLAC success was significantly higher in women with prior VBAC than that of women with VD prior to CD (83 % vs. 42 %, p < 0.01). ROC curve showed that the number of prior VBACs was a better predictor of TOLAC success and uterine rupture than the number of prior VD's. However, each single variable was found to have low positive predictive value (PPV) and requires other variables to improve the prediction. Finally, decision tree analysis demonstrated significant association between TOLAC success rate and prior VBAC, prior VD, and CD indications, without any association with the number of prior deliveries.

CONCLUSION

Prior VBAC has some prediction value for TOLAC success and uterine rupture. However, it has low PPV as a single variable and requires other variables to improve the prediction. The number of prior VDs is not improving prediction.