Recommendations for physical activity during pregnancy have progressed significantly in the last 30 years and continue to evolve as an increasing body of scientific evidence becomes available. In addition, there is an increasing number of women who wish to either maintain physical fitness levels during the prenatal period or initiate exercise for a healthier lifestyle during pregnancy. As such, consistent evaluation of the risks associated with exercise during pregnancy is warranted for maternal and fetal well-being. The primary purpose of this systematic review was to evaluate the scientific information available regarding maternal and fetal responses as it relates to the occurrence of adverse exercise-related events in pregnant women without contraindications to exercise. A systematic and evidence-based approach was used to analyze critically the level of evidence for risks associated with acute and chronic exercise during pregnancy in healthy pregnant women. All articles were screened according to standardized evaluation criteria developed by a panel of experts. A total of 74 investigations that involved 3766 pregnant women were included in the analysis. Of the 74 studies, only 35 studies documented the presence or absence of adverse events. The serious adverse event rate for these studies was 1.4 per 10 000 h of exercise. The adverse event rate increased to 6.8 per 10 000 h of exercise when including the occurrence of more mild events and exercise-related fetal bradycardia and tachycardia. Previously inactive or active women (without contraindications) are at a low risk for adverse fetal or maternal events if they participate in routine physical activity during pregnancy.