New method of contraceptive: How sperm-blocking vaginal gel can be alternative to IUDs

A vaginal gel has been used as an alternative to hormonal contraceptives to prevent sperm injected into female sheep.

Hormone-based birth control techniques, such as the pill and hormonal intrauterine devices (IUDs), are very effective but have some side effects, such as mood swings, decreased sex drive, sore breasts, nausea, and headaches.

However, these side effects are not there, non-hormonal methods such as condoms, diaphragms, and fertility tracking apps are less effective at preventing pregnancy.

At KTH Royal Institute of Technology in Sweden, Ulrike Schimpf and her colleagues have created a hormone-free vaginal gel that may function similarly to hormonal contraceptives without the negative side effects.

Chitosan, a biopolymer derived from fungi or crab shells, is the component of the gel. With the proteins secreted in cervical mucus, chitosan creates cross-links. As a result, sperm cannot pass the cervix and enter the fallopian tubes, where egg fertilisation takes place, because the mucus has thickened.

The gel was injected using a syringe applicator toward the backs of the sheep vagina, which are comparable to the human vagina. They artificially suckled each of the eight sheep tested with 1 billion sperm an hour later.

It was discovered that the gel had spread into the cervix's opening and throughout the vagina. Just two of the 1 billion swimming sperm were able to pass the cervix of one of the sheep in the study, proving that it formed an effective barrier.