Birth outcomes in women with body mass index of 40 kg/m 2 or greater stratified by planned and actual mode of birth: a systematic review and meta‐analysis

Pregnant women with a body mass index (BMI) ≥40 kg/m 2 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/m 2 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/m 2 , 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), I 2  = 0%) but lower risk for wound complications (7.6% vs 14.5%, P  < .001, numbers needed to treat (NNT = 15), I 2  = 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, I 2  = 0%), endometritis (5.1% vs 2.2%, P  < .001, NNH = 35, I 2  = 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, I 2  = 0%) and birth trauma (1.1% vs 0.2%, P  < .001, NNH = 111, I 2  = 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, I 2  = 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, I 2  = 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/m 2 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/m 2 and prior CD, repeat CD may be associated with better clinical outcomes.