Background: Clinical evidence indicates that women will benefit from regular physical activity during pregnancy. This study aimed to summarize and update the evidence on the effect of exercise on maternal gestational weight gain (GWG). Methods: We conducted a systematic literature search of Pubmed, Embase, and Cochrane Library from inception until July, 2018 for randomized controlled trials (RCTs) that investigate the effect of physical exercises on the maternalGWGcompared with that of no physical exercises or conventional medical care. We extracted data from eligible trials for study characteristics, interventions, patients' baseline characteristics and outcomes for the study populations of interest. We conducted meta-analyses using random effects models. Results: From 844 citations, 23 RCTs including 4462 pregnant women met the inclusion criteria. Meta-analysis indicated that compared with that in women having conventional medical care, GWG was significantly decreased in pregnant women with physical exercise [weighted mean difference (WMD) -1.02, 95% CI -1.35 to -0.70; P<.01; I-2=48.4%]. Women appeared to benefit more for gestational weight control for exercise frequency of 3 times per week (WMD = 1.22, 95% CI -1.55 to -0.90; I-2=40.3%) and exercise duration of 30 to 45 minutes each time (WMD -1.32, 95% CI -1.79 to -0.85; I-2=1.5%). Conclusion: This meta-analysis provides indications that exercise intervention can reduce maternal GWG for pregnant women, especially for those with exercise frequency of 3 times per week and duration of 30 to 45 minutes each time.