Hormonal Contraceptive Effects on the Vaginal Milieu: Microbiota and Immunity

Abstract

Hormonal contraceptives may influence the immunological and microbiological milieu of the vagina and alter the risk of acquisition of sexually transmitted infections (STIs) and human immunodeficiency virus (HIV). Most studies demonstrate more normal vaginal flora and less bacterial vaginosis in hormonal contraceptive users compared to non-users, suggesting that contraceptive-induced alteration in vaginal microbiota is an unlikely mechanism for increased risk of STI/HIV acquisition. Measured impacts of hormonal contraceptive use on the presence and activity of vaginal immune cells and vaginal cytokine secretion varies depending on the experimental model, progestogen used, contraceptive delivery method, and length of use of the method, limiting cohesive conclusions. Further study is needed to evaluate the effects of specific progestogens, delivery methods, and long-term use of contraceptives, particularly intrauterine devices and implants, on innate and adaptive immune cells and function in order to ultimately understand impacts on susceptibility to sexually transmitted infections including HIV.