From Contraceptives to Infertility Research – Understanding Cervical Mucus

Cervical mucus is a gel secreted in the cervical canal (cervix), acting as a protective barrier between the vagina and the uterus. The barrier is non-penetrable for sperms at most times of the menstrual cycle, but at the time of ovulation, the structure and chemical composition of the gel changes, allowing for sperm to pass through.

From contraceptives to infertility research

Ulrike Schimpf’s interest in the properties of cervical mucus started when she moved from Germany to Sweden and joined a research team dedicated to developing a safe, on-demand, and non-hormonal contraceptive.

– We tested how chitosan (a natural polymer) could interact with the mucins in cervical mucus, glycoproteins (natural polymers) that built a mesh, thereby hindering sperm passage at ovulation. Our lab tests showed that chitosan made the cervical mucus impenetrable to sperm, thereby suggesting that strengthening the mucus with chitosan could be an effective non-hormonal contraceptive method, Ulrike Schimpf explains.

This work sparked her interest in the opposite problem of reproduction: infertility. 

– One of the main issues contributing to infertility is when the mucin network in mucus becomes so dense that sperm simply cannot pass through. Interestingly, if we cen reinforce the mucus to prevent reproduce a loose network to enable it, Ulrike says. 

Why cervical mucus is difficult to study

Cervical mucus is heterogeneous and consists of different types of mucin polymers. It also contains various proteins, salts, cells, and is composed of 95–98 percent water. At ovulation, cervical mucus is highly elastic, difficult to cut, and loses water quickly through evaporation, making it challenging to prepare for scientific analysis.

In order to understand cervical mucus properly, advanced methods are needed, and to tackle these challenges, Ulrike uses the facilities at the Electron Microscopy Centre (EMC) at the Arrhenius Laboratory. The EMC hosts several advanced scanning electron microscopes (SEM), enabling researchers from many disciplines to study structures at molecular level.

– Working with SEM has been a great start. It gives me detailed images of the molecular structure. By combining SEM with energy-dispersive X-ray spectroscopy (EDS), I can get a good understanding of the chemical composition, Ulrike explains.

Exploring new ways of treating infertility

Ulrike is now developing improved preparation methods to preserve the natural structure of mucus samples. Her goal is to uncover new ways of treating mucus related infertility.

– Today, the primary available treatment is assisted reproduction such as in vitro fertilization (IVF). However, with a better understanding of the polymer structure and function of cervical mucus, perhaps we can find alternative treatments. Much is still unknown, and more research into women’s health is needed, Ulrike concludes.

Ulrike Schimpf will present some of her recent findings on 6th October at Stockholm Imaging Meeting 2025, a conference where leading researchers will present their latest findings and insights, with a particular focus on how the imaging facilities at Stockholm University has supported their work.