Effective family planning is critical for women’s empowerment and improvement in child and maternal health, yet nearly half of the world’s pregnancies are unintended(1), representing a clear unmet need for contraception. Hormonal contraceptive regimens offer high efficacy but may induce a systemic side effect profile that reduces compliance. New research into contraceptive development has stagnated since the 1980s, due to the exit of the U.S. pharmaceutical industry from the arena. Consequently, existing pericoital non-hormonal contraceptives, such as spermicides and gels, are unsatisfactory, suffering from high failure rates in typical use as well as high discontinuation rates, which partially stem from vaginal irritation and discomfort. To solve these issues, Schimpf and colleagues, reporting in Science Translational Medicine(2), proposed a novel mechanism that could represent the next generation in contraceptive design. They developed a formulation of chitosan mucoadhesive polymers that can be topically applied to physically reinforce the cervical mucus barrier against sperm penetration. Their vaginal gel formulation decreased average uterine sperm numbers after artificial insemination by 98% in a sheep model. Importantly, the mechanism was not spermicidal; rather, the chitosan physically cross-linked ovulatory cervical mucus to impair sperm penetration, without evidence of cytotoxicity, strong inflammatory response, or epithelial disruption, all of which can result from use of spermicides. In future work, the team plans to evaluate the contraceptive efficacy of their formulation, optimize its delivery, and perform a robust safety assessment, with attention to chronic toxicity and alterations to the vaginal microbiome. The researchers hope that their method will provide a path to overcome the “gas ceiling in efficacy” of existing non-hormonal contraceptive technologies.


Figure created by Logan Glasstetter with Vagina Diagram from BioRender



  1. ‘Staggering number’ of unintended pregnancies reveals failure to uphold women’s rights Unied Nations; 30 March 2022 [Available from: https://news.un.org/en/story/2022/03/1115062.
  2. Schimpf U, Caldas-Silveira E, Katchan L, Vigier-Carriere C, Lantier I, Nachmann G, et al. Topical reinforcement of the cervical mucus barrier to sperm. Science Translational Medicine.14(673):eabm2417.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.