Birth outcomes in women with body mass index of 40 kg/m2 or greater stratified by planned and actual mode of birth: a systematic review and meta-analysis

Abstract

Introduction: Pregnant women with a body mass index (BMI) ≥40 kg/m² are at an increased risk of requiring planned- and unplanned cesarean deliveries (CD). The aim of this systematic review is to compare outcomes in women with BMI ≥ 40 kg/m² based on planned and actual mode of birth.

Material and methods: Five databases were searched for English and French-language publications until February 2019, and all studies reporting on delivery outcomes in women with BMI ≥ 40 kg/m² , stratified by planned and actual mode of birth, were included. Risk-of-bias was assessed using the Newcastle-Ottawa Scale. Relative risks (RR) and 95% confidence intervals were calculated using random-effects meta-analysis.

Results: Ten observational studies were included. Anticipated vaginal birth vs planned CD (5 studies, n = 2216) was associated with higher risk for postpartum hemorrhage (13.0% vs 4.1%, P < .001, numbers needed to harm (NNH = 11), I² = 0%) but lower risk for wound complications (7.6% vs 14.5%, P < .001, numbers needed to treat (NNT = 15), I² = 58.3%). Planned trial of labor vs repeat CD (3 studies, n = 4144) was associated with higher risk for uterine dehiscence (0.94% vs 0.42%, P = .04, NNH = 200, I² = 0%), endometritis (5.1% vs 2.2%, P < .001, NNH = 35, I² = 0%), prolonged hospitalization (one study, 30.3% vs 26.0%, P = .003, NNH = 23), low five-minute Apgar scores (4.9% vs 1.7%, RR 2.95 (2.03, 4.28), NNH = 30, I² = 0%) and birth trauma (1.1% vs 0.2%, P < .001, NNH = 111, I² = 0%). Successful vaginal birth vs intrapartum CD (n = 3625) was associated with lower risk of postpartum hemorrhage (15.1% vs 70%, P < .001, NNT = 2, I² = 0%), wound complications (one study, 0% vs 4.4%, P = .007, NNT = 23), prolonged hospitalization (one study, 1.9% vs 6.7%, 0.04, NNT = 21) and low five-minute Apgar scores (one study, 1.0% vs 5.6%, P = .03, NNT = 22), but more birth trauma (5.9% vs 0.6%, P = .005, NNH = 19, I² = 0%). Compared groups had dissimilar demographic characteristics. Although studies scored 6-7/9 on risk-of-bias assessment, they were at high-risk for confounding by indication.

Conclusions: Evidence from observational studies suggests clinical equipoise regarding the optimal mode of delivery in women with BMI ≥ 40 kg/m² and no prior CD. This question is best answered by a randomized trial. Based on an unplanned subgroup analysis, for women with BMI ≥ 40 kg/m² and prior CD, repeat CD may be associated with better clinical outcomes.

Keywords: Class-III Obesity; cesarean delivery; meta-analysis; mode of delivery; pregnancy; pregnancy complications; systematic review; vaginal birth.