Background: To summarize evidence of benefits and risks of maternal and neonatal outcomes among pregnant women after Roux-en-Y gastric bypass surgery. Methods: A systematic search was conducted in MEDLINE, EMBASE, Web of Science, Ovid and Cochrane Library until 24th May 2021. Inclusion criteria were randomized trails or observational studies including at least one of maternal or neonatal outcomes from pregnant women who had a history of Roux-en-Y gastric bypass surgery with a control group of pregnant women with no history of bariatric surgery. Non-English studies were excluded. Both fixed-effect and random-effect models were used in the meta-analyses. Newcastle-Ottawa Scale was used to assess quality of studies. Results: Twelve retrospective articles were eligible including 13 848 pregnant women with a history of Roux-en-Y gastric bypass surgery and 255 008 pregnant women without a history of bariatric surgery. The results of meta-analysis showed a lower incidence of preterm premature rupture of membranes (OR 0.53, 95% CI [0.47, 0.60], p < 0.00001), large gestational age infants (OR 0.28, 95%CI [0.22, 0.37], p < 0.00001) or macrosomia (OR 0.26, 95%CI [0.23, 0.30], p < 0.00001) in women after Roux-en-Y gastric bypass surgery. On the other hand, infants born to mothers with a history of Roux-en-Y gastric bypass surgery had an increased risk of small gestational age (OR 2.24, 95% CI [1.55, 3.24], p < 0.00001). Conclusion: Roux-en-Y gastric bypass surgery reduces significantly of risks of preterm premature rupture of membranes and large for gestational age/ macrosomia, but increase the risk of small for gestational age. (C) 2021 Elsevier B.V. All rights reserved.