(570) Association of BMI and success of Trial of Labor After Cesarean: Systematic Review and Meta-Analysis

Thursday, February 9, 2023

4:00 PM – 5:30 PM

Objective: Maternal obesity is known to impact success rates of trial of labor after a cesarean (TOLAC). The objective of this study was to pool data to determine the impact of BMI class on TOLAC success.

Study Design: The review was based on a pre-defined protocol which was registered in PROSPERO (CRD42022308317). Studies were selected if they were published from 1990-2021, written in English, included participants aged 16 to 50, and included pregnant persons who had a prior cesarean and underwent a TOLAC. A comprehensive literature search was performed by a research services librarian. 789 references were screened at the title and abstract level, 72 full text articles were reviewed, and 12 articles were chosen for the meta-analysis. The primary outcome was failed TOLAC and delivery by repeat cesarean. Data on BMI (standard groups) cross-classified by TOLAC outcome was extracted from each study and entered into Revman. Associations were expressed as random-effect risk ratio (RR) with 95% confidence interval (CI), and studies were weighted by the inverse-variance method. Interstudy heterogeneity was assessed based on the I² statistic, with I² ³50% indicative of heterogeneity.

Results: Rates of repeat cesarean in participants undergoing TOLAC increased as BMI increased: BMI ³25 kg/m² (RR 1.37, 95% CI 1.25, 1.49; I² = 29%; 8 studies), BMI ³30 kg/m² (RR 1.5, 95%CI 1.27, 1.76; I² = 92%; 11 studies), BMI ³40 kg/m² (RR 1.67, 95% CI 1.45, 1.91) (see Table). Rates of repeat cesarean were also higher in overweight (BMI 25-29.9 kg/m²) compared to normal weight participants (BMI < 25 kg/m²) (RR 1.25, 95% CI 1.14, 1.36; I² = 18%; 8 studies), and in obesity class I (BMI ³30 kg/m²) compared to those with normal BMI (RR 1.56, 95% CI 1.35, 1.80; I² = 62%; 8 studies) (see Figure).

Conclusion: Increase in maternal pre-pregnancy BMI is associated with a corresponding increase in the risk for delivery by repeat cesarean in patients undergoing TOLAC. This work highlights the impact that weight loss may have on improving future pregnancy outcomes and increasing the chance for TOLAC success.

Primary & Presenting Author(s)

Morgan C. Dunn, MD (she/her/hers)
Resident
Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, United States

Coauthor(s)

CA
Cande V. Ananth, MPH, PhD
Professor and Vice Chair for Academic Affairs, Department of Obstetrics, Gynecology, and Reproductive Sciences
Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, United States
YZ
Yingting Zhang, N/A
Robert Wood Johnson Library of the Health Sciences
New Brunswick, New Jersey, United States
HS
Haylea Sweat Patrick, MD
Department of Maternal Fetal Medicine, Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, United States