The association between obesity and the success of trial of labor after cesarean delivery (TOLAC) in women with past vaginal delivery

Objectives To evaluate the effect of overweight (body mass index; BMI 25.0–29.9 kg/m2), and obesity (BMI>30 kg/m2), on the success of trial of labor after cesarean delivery (TOLAC), with consideration of successful past vaginal birth. Methods This retrospective cohort study was performed using electronic database of obstetrics department at a university-affiliated tertiary medical center. All women admitted for TOLAC at 37–42 weeks of gestational age, carrying a singleton live fetus at cephalic presentation, with a single previous low segment transverse cesarean delivery between 1/2015 and 5/2021 were included. Primary outcome was the rate of cesarean delivery during labor, and subgroup analysis was performed for the presence of past vaginal birth. Results Of the 1200 TOLAC deliveries meeting the inclusion criteria, 61.9 % had BMI in the normal range, 24.6 % were overweight (BMI 25.0–29.9 kg/m2), and 13.4 % were obese (BMI of 30 kg/m2 and over). Using a multivariate analysis, BMI≥30 kg/m2 was associated with increased risk of cesarean delivery compared to normal weight. However, in the subgroup of 292 women with a history of successful vaginal birth BMI did not affect TOLAC success. Conclusions BMI does not affect the success of TOLAC in women with previous vaginal birth. This information should be considered during patients counselling, in order to achieve a better selection of mode of delivery and higher patients’ satisfaction.