After decades of false starts, researchers say they are finally making progress on a long-acting and reversible birth control option for men. The experimental product is a hormonal gel that men rub on their shoulders once daily. Over time, it blocks the production of sperm in the testes.
The gel was developed by the National Institutes of Health and the nonprofit Population Council, and it takes much the same approach as birth control pills for women. It uses two hormones: nestorone, a progestin, and testosterone, the male sex hormone. The nestorone suppresses the production of testosterone in the testes and, with it, the development of sperm.
But testosterone serves many functions in the body: It is responsible for muscle maintenance and libido, for example, and men need some in their circulation to function normally. The gel replaces enough to keep them healthy but not so much that they make enough sperm to get someone pregnant. Researchers have been formulating and refining the dose and concentration of the gel since 2005.
In this latest test, which included more than 300 couples, they think they got it right. Normal sperm counts range from about 15 million to 200 million sperm per milliliter of semen, and studies have shown that sperm counts of less than 1 million per milliliter are low enough to prevent pregnancy. In a , 86% of men achieved these low sperm counts by 15 weeks of using the gel.
For some, it worked even faster, suppressing sperm production within four to ei.
