BACKGROUND: Weight gains in pregnancy within the recommended guidelines are associated with healthy fetal and maternal outcomes; higher weight gains are associated with fetal macrosomia. This study was a systemic review of randomized controlled trials on the effect of aerobic training on maternal weight in pregnancy. METHODS: The study data source was publications through May 2012 in the MEDLINE (PubMed) database. The citation lists of randomized controlled trials on the effect of aerobic training and maternal weight were extracted. Data on participants' characteristics, study quality, population, intervention, treatment outcome (maternal weight gain) were collected and analyzed. RESULTS: There were 11 randomized controlled studies using body weight (kg) as measure of treatment outcome. A total of 1177 subjects were recruited in the 11 studies. The mean± SD weight gain (kg) for the exercise (11.31± 7.44kg) and control (14.42± 6.60kg) groups; Meta-analysis result indicated significant effect of aerobic training on maternal weight (t= -7.580, p= .000) at p< 0.05. CONCLUSION: It was concluded that aerobic training is an effective tool in maternal weight gain control in pregnancy. More randomized controlled trials are warranted.