8 Male Contraceptives and Non-Hormonal Methods
Contents
Introduction
Male contraceptives, also called male birth control, are methods of preventing pregnancy that rely on the male partner. Many pregnancies worldwide are unintended.
Unintended pregnancies happen when couples don't use contraception, have trouble using a method correctly, or a method fails. In many low-income countries, access to contraception is also limited by cost and culture.
The main male contraceptive options today are condoms, vasectomy, withdrawal and outercourse. An ideal male contraceptive would be easy to get, affordable, easy to use, free of serious side effects, not affect libido, and fully reversible.
Surveys in many countries suggest that a large share of men and women would welcome new male contraceptive options.
However, religious, educational, economic and cultural barriers still stand in the way of male contraceptives. Most contraceptive research has focused on methods for women, and some male contraceptive trials have been stopped early.
Even so, both hormonal and non-hormonal male methods are being actively studied. Several are in human clinical trials, but none has been approved yet.
Male contraceptives methods
1. Vasectomy
A vasectomy is a minor surgery, usually done under local anesthesia. The surgeon cuts, closes or blocks the vas deferens, the tubes that carry sperm from the testicles. It is a safe outpatient procedure used worldwide.
In the "no-scalpel" technique, the surgeon reaches the vas deferens through a tiny puncture in the scrotum instead of an incision.
The no-scalpel technique causes less bleeding and has low rates of infection. Vasectomy is one of the most effective methods: the CDC lists a typical-use failure rate of about 0.15% in the first year.
Vasectomy doesn't work right away. It can take up to three months to become fully effective, so couples need a backup method, like condoms, until a semen test confirms there are no sperm.
Vasectomy should be considered permanent. Reversal surgery is possible but not always successful, and success rates fall as more time passes after the vasectomy.
Some men develop antisperm antibodies after vasectomy, which can lower fertility even after a reversal. In experienced hands, complications like bleeding and infection are uncommon. A small number of men have lasting testicular pain after the procedure.
2. Retrograde ejaculation
Intentional retrograde ejaculation, sometimes called coitus saxonicus, is an old practice. It involves pressing on the perineum during orgasm so semen goes into the bladder instead of out of the body.
It is not a reliable form of contraception and is not recommended as a birth control method.
3. Condoms
A condom is a sheath-shaped barrier device used during sex to reduce the chance of pregnancy. It is rolled onto an erect penis before intercourse and blocks semen from entering the partner's body.
With perfect use, about 2% of couples get pregnant in a year. With typical use, the CDC puts the failure rate at about 13%.
Latex and polyurethane condoms also reduce the risk of sexually transmitted infections, while lambskin condoms do not. Condoms can be combined with other methods, such as spermicide, for greater protection.
4. Non-hormonal method
Non-hormonal male contraceptives aim to block sperm production in the testes, sperm maturation in the epididymis, or sperm movement. They could avoid the side effects of hormones, which makes them attractive.
Most are still experimental. The furthest along is YCT-529, an oral pill that blocks a receptor for retinoic acid, a form of vitamin A that sperm production depends on. A first human safety study in 16 men found single doses well tolerated, and a longer dosing trial was underway.
On the hormonal side, the National Institutes of Health and the Population Council are testing a daily Nestorone and testosterone (NES/T) gel in couples. None of these methods is available yet.
5. Triptolide
Triptolide is an extract from the Chinese herb Tripterygium wilfordii, which was shown to reduce sperm motility and count. However, in animal experiments the effects were irreversible, and the compound also suppresses the immune system.
6. Indenopyridines
Indenopyridines are experimental compounds that affect Sertoli cells and developing sperm cells in the testes. Studies of one indenopyridine, CDB-4022, found that it disrupts how Sertoli cells hold on to developing sperm, leading to the loss of those cells.
When it was combined with a gonadotropin-releasing hormone (GnRH) antagonist, it caused reversible infertility in male rats. Hormone levels were unaffected, and no obvious toxic effects were seen when the drug was given to monkeys. It has not been tested as a contraceptive in men.
7. Adjudin
Adjudin is a derivative of lonidamine, which was developed as an anticancer drug. Adjudin disrupts the attachment between Sertoli cells and developing sperm. The effect was quite rapid, and immature sperm cells detached within days of treatment in rats.
Other changes included shrinking of the Sertoli cells and abnormal sperm cells. Muscle atrophy and liver inflammation were seen in male rats treated with adjudin.
To avoid these effects, researchers tried attaching adjudin to a modified follicle-stimulating hormone (FSH) protein so the drug would go mainly to the testes. This lowered overall drug exposure while still causing infertility in animals. It has not reached human trials.
8. Epididymis targets
Sperm mature as they pass through the epididymis before ejaculation, so the epididymis is another possible contraceptive target. Genetic studies in mice have identified several candidate targets, but none has reached clinical testing in humans or nonhuman primates.
Epididymis-specific proteins could provide points for drug development. For example, the G protein-coupled receptor HE6 appears only in the ducts of the epididymis, and mice lacking HE6 are infertile but otherwise normal. HE6 seems important for fluid reabsorption in these ducts, though its exact role isn't clear.
Similarly, CRISP-1, a member of the cysteine-rich secretory protein family, appears mainly in the epididymis. It is secreted into the epididymis, where it is thought to interact with spermatozoa and keep them from maturing too early during storage.
Drugs based on these proteins are still years away. Researchers first need to find safe, specific inhibitors and confirm that they work in the reproductive tract.
The outlook for male contraceptives
Contraception plays a key role in family planning. Despite years of research, no new male contraceptive has reached the market, so men's choices remain limited.
Most men who use contraception today choose condoms or vasectomy. Hormonal methods that combine a progestin with testosterone, such as the NES/T gel, have shown promising results in trials. Non-hormonal pills like YCT-529 are also in human testing.
Talk with a healthcare provider about which method fits your needs.
HP Thoughts: Are you aware that birth control implants exist? Could they put you at risk or not? Read our article to find out: Contraceptive Implant.
