Birth outcomes in women with body mass index of 40 kg/m<sup>2</sup> or greater stratified by planned and actual mode of birth: a systematic review and meta‐analysis
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.019 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.015 | 0.032 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".