Systematic Review|Articles in Press, 100914

Prepregnancy Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy: A Systematic Review, Pairwise, and Network Meta-Analysis of Obstetrical and Neonatal Outcomes



      To systematically investigate a wide range of obstetrical and neonatal outcomes in respect to two types of pre-pregnancy bariatric surgery: Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) through 1. providing a meta-analysis of the effect of  bariatric surgery (RYGB vs no surgery and, separately, SG vs no surgery) on adverse obstetric and neonatal outcomes, and 2) to compare the relative benefit of RGYB vs. SG using both conventional meta-analysis and network meta-analysis.

      Data sources

      We searched PubMed, Scopus, and Embase systematically from inception up to April 30, 2021

      Study eligibility criteria

      Studies reporting on pregnancies’ obstetrical and neonatal outcomes in respect to two types of pre-pregnancy bariatric surgery including RYGB and SG. Included studies either indirectly compared between the procedure and control or directly compared between the two procedures.


      We performed a systematic review followed by pairwise and network meta-analysis (NMA) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In the pairwise analysis, multiple obstetrical and neonatal outcomes were tabulated and compared between three types of groups 1) RYGB vs controls, 2) SG vs controls, and 3) RYGB vs SG. Primary outcomes included small for gestational age (SGA), large for gestational age (LGA), gestational hypertension (GHTN)/preeclampsia (PE), and gestational diabetes (GDM). Secondary outcomes included preterm birth (PTB), anemia, cesarean delivery (CD), and biochemical profile. The random-effect model was used to pool the mean differences or odds ratios (OR) and the corresponding 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 value. Newcastle Ottawa Scale (NOS) was used to assess individual study quality. To resolve inconclusive findings and to rank current treatments, NMA was conducted for the primary outcomes. Quality of the evidence was assessed with the Confidence in NMA approach and Grading of Recommendations, Assessment, Development and Evaluations tool within the summary of findings table.


      Total of 20 studies were included reporting on 40,108 pregnancies of which 5,194 underwent RYGB, 405 underwent SG, and 34,509 were controls. Compared to controls, RYGB increased SGA infants (OR: 2.56 (95% CI 1.77, 3.70), I2 29.1%, P<<0.00001), decreased LGA (OR: 0.25 (95% CI 0.18, 0.35), I2 0%, P<0.00001), decreased GHTN/PE (OR: 0.54 (95% CI 0.30, 0.97), I2 26.8%, P=0.04), decreased GDM (OR: 0.43 (95% CI 0.23, 0.81), I2 32%, P=0.008), increased maternal anemia (OR: 2.70 (95% CI 1.53, 4.79), I2 40.5%, P<0.001), increased NICU admission (OR: 1.36 (95% CI 1.04, 1.77), I2 0%, P=0.02), and lower mean gestational weight gain (GWG) (Mean difference: -3.37 kg (95% CI -5.62, -1.11), I2 65.3%, P=0.003). Only 3 studies compared SG to control with no significant differences in primary outcomes or in mean GWG. The NMA showed that RYGB (malabsorptive procedure) resulted in greater decrease of LGA, GHTN/PE, and GDM and a greater increase in SGA infants when compared to SG (restrictive procedure). However, small number of studies, small number of SG patients, limited outcomes, and data heterogenicity resulted in low-to-moderate network GRADE of evidence.


      This NMA showed that RYGB resulted in greater decrease in LGA, GHTN/PE, and GDM compared to SG, but at the same time it resulted in greater increase SGA infants. Certainty of evidence was low-to-moderate network GRADE of evidence. Evidence is still lacking for periconception biochemical profile, congenital malformations, and reproductive health outcomes between both interventions; thus, future well-designed prospective studies are needed to further characterize these outcomes.


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