Comparison of Combined Parenteral and Oral Hormonal Contraceptives: A Systematic Review and Meta-Analysis of Randomized Trials

Abstract

Background: Delivering contraceptive hormones through a transdermal patch or a vaginal ring might have advantages over the traditional oral route. Objectives: To compare the effectiveness, compliance, and side effect profile of oral and parenteral drug administration methods. Methods: We performed a systematic literature search in four medical databases—MEDLINE (via PubMed), Cochrane Library (CENTRAL), Embase, and Scopus—from inception to 20 November 2022. Randomized controlled trials assessing the efficacy, compliance, and adverse event profile of combined parenteral and oral hormonal contraceptives were included. Results: Our systematic search provided 3952 records; after duplicate removal, we screened 2707 duplicate-free records. A total of 13 eligible studies were identified after title, abstract, and full-text selection. We observed no significant difference in contraceptive efficacy (Pearl Index) between oral and parenteral drug administration (MD = −0.06, CI: −0.66–0.53; I2 = 0%). We found significant subgroup differences between parenteral methods in terms of compliance (χ2 = 4.32, p =0.038, I2 = 80%) and certain adverse events: breast discomfort (χ2 = 19.04, p =0.001, I2 = 80%), nausea (χ2 = 8.04, p =0.005, I2 = 75%), and vomiting (χ2 = 9.30, p =0.002; I2 = 72%). Conclusion: Both parenteral and oral contraceptives can be used as an effective contraceptive method, and the route of administration should be tailored to patient needs and adverse event occurrence.