Cervical mucus and contraception: what we know and what we don't.

OBJECTIVES: Cervical mucus varies in response to both natural and artificial hormonal changes. It is commonly believed that cervical mucus thinning is associated with normal fertility and that progestogen-induced thickening is an essential contraceptive mechanism. This review aims to broadly summarize our current knowledge about cervical mucus from both a clinical and basic research perspective.

STUDY DESIGN: We reviewed published literature pertinent to cervical mucus and contraception across scientific disciplines. We first present the most current understanding of the composition of cervical mucus, how it is hormonally regulated, and examine the role of mucus as an immune barrier. We then critically assess the current clinical tests used as surrogate markers for a contraceptive effect. Finally, we review contraceptive studies that have specifically focused on cervical mucus changes.

RESULTS: Existing research suggests that cervical mucus has potential to be a contraceptive target with unique, multipurpose characteristics. However, methodologic limitations associated with clinical assessments of cervical mucus complicate our understanding of contraceptive treatment effects. Key pathways involved in cervical mucus production with potential as novel nonhormonal contraceptive targets have been identified.

CONCLUSIONS: More research is needed to clarify the role of cervical mucus in current hormonal contraceptives and to support the development of novel nonhormonal cervix-based methods.