Preceding studies have demonstrated that periodontitis might increase the liability of adverse pregnancy outcomes such as preterm birth, preeclampsia, low birth weight, and perinatal fatality in pregnant women. Nonetheless, there is no convincing testimony that periodontitis is related directly to adverse pregnancy outcomes in pregnant women. This systematic review intended to assess and review all the available randomized clinical trials that concentrated on the association between periodontal diseases and adverse pregnancy outcomes, and the impact of periodontal disease therapy on adverse pregnancy outcomes. The databases like Scopus, PubMed, Google Scholar, and Web of Science were consumed to explore relevant and suitable studies after adopting the inclusion and exclusion criteria. The search included articles with no time restrictions and certain keywords were utilized in the databases. The investigation was done through four independent reviewers employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Twenty-three studies fulfilled the exclusion and inclusion criteria and were used and included in this systematic review. The above-mentioned studies assessed the association between periodontal diseases and adverse pregnancy outcomes and the effect of periodontal disease treatment in reducing the influence of adverse pregnancy outcomes. This systematic review revealed that there is a relationship between periodontitis and adverse pregnancy outcomes, and periodontal treatment has a reducing impact on adverse pregnancy outcomes in pregnant women with periodontitis. Prospect studies are warranted to investigate the relationship between periodontitis and different adverse pregnancy outcomes and to decide the best type and the most effective therapy to treat periodontitis in pregnant women.