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Objective This study aimed to compare adverse neonatal outcomes associated with the trial of labor after cesarean (TOLAC) at term in pregnancies according to maternal prepregnancy body mass index (BMI; kg/m2) and the presence of previous vaginal delivery (VD).

Study Design This was a repeated cross-sectional analysis of individuals with singleton, cephalic, and term deliveries with a history of one or two cesarean deliveries in the Linked Birth/Infant Death data from 2011 to 2020. Outcomes were examined according to the BMI category including BMI <30, 30 to 39.9, and 40 to 69.9 kg/m2. The primary outcome was a composite neonatal outcome, defined as any presence of neonatal death, neonatal intensive care unit admission, assisted ventilation, surfactant therapy, or seizures. Outcomes were compared between TOLAC and elective repeat cesarean delivery (eRCD) after stratifying by BMI category and previous VD. Log-binomial regression was performed to obtain adjusted relative risk (aRR) with 99% confidence intervals, controlling for covariates.

Results Of 4,055,440 individuals, 2,627,131 had BMI <30 kg/m2, 1,108,278 had BMI 30 to 39.9 kg/m2, and 320,031 had BMI 40 to 69.9 kg/m2. In individuals with no previous VD, VD rates after TOLAC were 66.7, 57.2, and 48.1%, respectively. In individuals with previous VD, VD rates after TOLAC were 81.4, 74.7, and 67.3%, respectively. In individuals without previous VD, compared with those who had an eRCD, those who had TOLAC were more likely to experience composite neonatal outcomes in individuals with BMI < 30 kg/m2 (5.0 vs. 6.5%; aRR 1.33 [1.30–1.36]), BMI 30 to 39.9 kg/m2 (6.1 vs. 7.8%; aRR 1.29 [1.24–1.34]), and BMI 40 to 69.9 kg/m2 (8.2 vs. 9.0%; aRR 1.15 [1.07–1.23]). In individuals with previous VD, there was no difference in the composite neonatal outcomes in BMI < 30 kg/m2 (6.2 vs. 5.8%; aRR 0.98 [0.96–1.00]), BMI 30 to 39.9 kg/m2 (7.4 vs. 7.1%; aRR 0.99 [0.95–1.02]), and BMI 40 to 69.9 kg/m2 (9.4 vs. 8.7%; aRR 0.96 [0.91–1.02]).

Conclusion TOLAC among obese individuals could be offered in selected cases.

Key Points

TOLAC among obese individuals could be offered selectively, despite their reduced likelihood of attempting or succeeding at it.

Higher BMI individuals show decreased rates of both attempting and achieving successful TOLAC.

Despite these trends, attempting TOLAC after a previous vaginal delivery does not heighten neonatal complications.

Keywords morbid obesity - neonatal death - previous vaginal delivery - severe maternal morbidity - TOLAC - vaginal birth after cesarean - VBAC Note

This paper will be presented in part as a poster at the SMFM 2024 Pregnancy Meeting, National Harbor, MD, from February 10–14, 2024.

Publication History

Received: 11 February 2024

Accepted: 11 March 2024

Accepted Manuscript online:
12 March 2024

Article published online:
04 April 2024

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