Published On February 27, 2020
FOR THE PAST YEAR AND A HALF, researchers at nine institutions have been recruiting couples to help test a novel kind of birth control. It’s a topical gel for men. When applied daily to the shoulders, it should achieve the tricky balancing act of limiting sperm production while maintaining testosterone levels—reducing the risk of pregnancy without inhibiting libido. If the gel reduces a man’s sperm count during the first two to four months, then the couple will use it as their only means of birth control for the rest of the trial.
Contraception is long overdue for a revolution, says Boston University School of Medicine microbiologist Deborah Anderson, who recently made that argument in a New England Journal of Medicine editorial. Although current birth control methods work reasonably well, they are far from ideal—and to judge by the rates of unplanned pregnancies, they are often ineffective.
According to the World Health Organization, about one-quarter of all pregnancies in low and middle-income countries are unplanned. And in the United States, an estimated 45% of pregnancies are unintended each year. One reason may be problems of access. Although condoms are generally available, other contraceptives require doctors’ prescriptions or invasive procedures, obstacles that put them out of reach for some people, says Anderson.
Hormonal birth control methods, including contraceptive pills and implants, may also need a second look, since they don’t work for everyone and can have potentially serious side effects. A few studies have shown changes in brain structure and function in women using those methods, and a study from December 2019 showed changes specifically in the hypothalamus, the implications of which are still unclear. Hormonal birth control can also increase the risk of blood clots, as well as imbalances in the microbiome, which can put users at a higher risk for Crohn’s disease.
A male contraceptive could change the landscape of birth control. The topical gel, now in advanced clinical trials, is the most developed, but other ideas are also being worked on, some since the early 1990s. “We always seem to be five to 10 years away from a product,” says University of Washington endocrinologist Arthi Thirumalai, who is helping oversee testing of the gel at one trial site. In addition, she and her collaborators are testing two promising oral contraceptives for men, and other labs are looking into injections, pills and patches.
Anderson thinks that the consumer market may at last be ready for a male contraceptive. “Questionnaires show that a substantial proportion of men are interested in taking control of their own contraception,” she says. She would like to see a buffet of birth control options for men and women, all available over the counter. New choices for women in low-income countries are especially important, she says.
In her lab at BU, Anderson has been developing a plant-based, vaginal film that can act as a contraceptive and protect a woman against sexually transmitted diseases—an example of “multipurpose prevention technology,” or MPT. She says she got the idea to work on an MPT about a decade ago, when she learned about monoclonal antibodies—immunotherapy drugs that trigger the body’s own defenses—being used to fight cancer and other diseases.
To produce the monoclonal antibodies for her product, Anderson is investigating plantibodies—“antibodies that can be created through a plant platform, which is really cost-effective and fast,” she says. The hope is that her team can engineer substances that can not only prevent pregnancy but also ward off human immunodeficiency virus type 1 (HIV-1) and herpes simplex viruses. She also wants the final product to be safe enough to offer over the counter. “I’m excited to introduce methods that aren’t dependent on hospitals or physicians,” she says.
UW’s Thirumalai sees the whole field of contraception at a tipping point. “People are much more interested in developing and trying new methods today than they were 20 years ago,” she says. “I think research is going to continue at a faster rate.”
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