Introduction: C-reactive protein (CRP) during pregnancy has been associated with adverse maternal outcomes such as preeclampsia and gestational diabetes mellitus. Increased physical activity and exercise training have shown to decrease circulating levels of CRP. The association between maternal exercise and CRP has not been adequately investigated. Objective: To review the literature to investigate the maternal exercise effects on CRP responses during pregnancy. Methods: This systematic review was designed according to PRISMA (PROSPERO registration CRD42016039618). Eligible studies were identified from MEDLINE, EMBASE, Web of Science, Scopus, COCHRANE CENTRAL, Scielo and SportDiscus up to May 2016 without year of publication and language limitations. The main MeSH terms were the following: “exercise”, “motor activity”, “physical activity”, “pregnancy”, “gestational”, “maternal” and “C-reactive protein”. Inclusion criteria were studies conducted in pregnant women who were engaged in any type of exercise or physical activity and report CRP values. The extraction and risk of bias assessment were carried out by two independent reviewers. A total of 344 studies were found, 147 of which were excluded as duplicates, and 191 studies were excluded based on title, abstract and full-text. Six studies met the inclusion criteria and were included in the present systematic review. Results: Across six studies, 1276 pregnant women were included. The maternal exercise intensity ranged from light to vigorous. Out of six studies, two were randomized controlled trials that reported decrease in maternal CRP concentrations after an exercise intervention. Four studies were prospective observational studies that reported no difference in maternal CRP values with exercise (one study) or decrease in maternal CRP values when the exercise was added to the prenatal standard care. Conclusion: In conclusion, the majority of the studies found in the present systematic review reported a decrease in CRP concentrations after an exercise intervention before or during pregnancy. These responses indicate a trend towards a protective effect of exercise and physical activity on inflammation during pregnancy.