Pregnancy prevention methods used by men
Male contraceptives, also known as male birth control, are methods of preventing pregnancy by interrupting the function of sperm. The main forms of male contraception available today are condoms, vasectomy, and withdrawal, which together represented 20% of global contraceptive use in 2019. New forms of male contraception are in clinical and preclinical stages of research and development, but as of 2024, none have reached regulatory approval for widespread use.
These new methods include topical creams, daily pills, injections, long-acting implants, and external devices, and these products have both hormonal and non-hormonal mechanisms of action. Some of these new contraceptives could even be unisex, or usable by any person, because they could theoretically incapacitate mature sperm in the man's body before ejaculation, or incapacitate sperm in the body of a woman after insemination.
Background.
In the 21st century, surveys indicated that around half of men in countries across the world have been interested in using a variety of novel contraceptive methods, and men in clinical trials for male contraceptives have reported high levels of satisfaction with the products. Women worldwide have also shown a high level of interest in new male contraceptives, and though both male and female partners could use their own contraceptives simultaneously, women in long-term relationships have indicated a high degree of trust in their male partner's ability to successfully manage contraceptive use.
A modelling study from 2018 suggested that even partial adoption of new male contraceptives would significantly reduce unintended pregnancy rates around the globe, which remain at nearly 50%, even in developed countries where women have access to modern contraceptives. Unintended pregnancies are associated with negative socioeconomic, educational, and health outcomes for women, men, and the resulting children (especially in historically marginalized communities), and 60% of unintended pregnancies end in abortions, many of which are unsafe and can lead to women's harm or death. Therefore, the development of new male contraceptives has the potential to improve racial, economic, and gender equality across the world, advance reproductive justice and reproductive autonomy for all people, and save lives.
Available methods.
Vasectomy.
Vasectomy is surgical procedure for permanent male sterilization usually performed in a physician's office in an outpatient procedure. During the procedure, the vasa deferentia of a patient are severed, and then tied or sealed to prevent sperm from being released during ejaculation. Vasectomy is an effective procedure, with less than 0.15% of partners becoming pregnant within the first 12 months after the procedure. Vasectomy is also a widely reliable and safe method of contraception, and complications are both rare and minor. Vasectomies can be reversed, though rates of successful reversal decline as the time since vasectomy increases, and the procedure is technically difficult and often costly.
Condoms.
A condom is a barrier device made of latex or thin plastic film that is rolled onto an erect penis before intercourse and retains ejaculated semen, thereby preventing pregnancy. Condoms are less effective at preventing pregnancy than vasectomy or modern methods of female contraception, with a real-world failure rate of 13%. However, condoms have the advantage of providing protection against some sexually transmitted infections such as HIV/AIDS. Condoms may be combined with other forms of contraception (such as spermicide) for greater protection.
Withdrawal.
The withdrawal method, also known as "coitus interruptus" or pulling out, is a behavior that involves halting penile-vaginal intercourse to remove the penis out and away from the vagina prior to ejaculation. Withdrawal is considered a less-effective contraceptive method, with typical-use failure rates around 20%. However, it requires no equipment or medical procedures.
Research into new methods.
Researchers have been working to generate novel male contraceptives with diverse mechanisms of action and possible delivery methods, including long-acting reversible contraceptives (LARCs), daily transdermal gels, daily and on-demand oral pills, monthly injectables, and implants. Efforts to develop male contraceptives have been ongoing for many decades, but progress has been slowed by a lack of funding and industry involvement. As of 2024, most funding for male contraceptive research is derived from government or philanthropic sources.
Novel male contraceptives could work by blocking various steps of the sperm development process, blocking sperm release, or interfering with any of the sperm functions necessary to reach and fertilize an egg in the female reproductive tract. Advantages and disadvantages of each of these approaches will be discussed below, along with relevant examples of products in development.
Methods that block or interfere with sperm production.
These methods work by preventing the testes from producing sperm, or interfering with sperm production in a way that leads to the production of nonfunctional sperm. This approach can be accomplished by either hormonal or nonhormonal small-molecule drugs, or potentially by thermal methods. The effectiveness of contraceptives in this group can be easily assessed microscopically, by measuring sperm count or abnormalities in sperm shape, but because spermatogenesis takes approximately 70 days to complete, these methods are likely to require approximately three months of use before they become effective, and approaches that halt sperm production at an early stage of the process may result in reduced testicular size. Methods have been suggested in the 1980s.
Hormonal male contraceptives.
Hormonal contraceptives for men work similarly to hormonal female methods, using steroids to interrupt the hypothalamic-pituitary-gonadal axis and thereby block sperm production. Administering external androgens and progestogens suppresses secretion of the gonadotropins LH and FSH, which impairs testosterone production and sperm generation in the testes, leading to reduced sperm counts in ejaculates within 4–12 weeks of use. However, since the contraceptives contain testosterone or related androgens, the levels of androgens in the blood remain relatively constant, thereby limiting side effects and maintaining masculine secondary sex characteristics like muscle mass and hair growth.
Multiple methods of male hormonal contraception have been tested in clinical trials since the 1990s, and although one trial was halted early, leading to a large amount of press attention, most hormonal male contraceptives have been found to be effective, reversible, and well-tolerated.
In clinical trials.
As of 2024[ [update]], the following hormonal male contraceptive products are in clinical trials:
Some anabolic steroids may exhibit suppressive effects on spermatogenesis, but none are being investigated for use as a male contraceptive.
Non-hormonal male contraceptives.
Non-hormonal contraceptives for men are a diverse group of molecules that act by inhibiting any of the many proteins involved in sperm production, release, or function. Because sperm cells are highly specialized, they express many proteins that are rare in the rest of the human body. This suggests the possibility that non-hormonal contraceptives that specifically block these sperm proteins could have fewer side effects than hormonal contraceptives, since sex steroid receptors are found in tissues throughout the body. Non-hormonal contraceptives can work by blocking spermatogenesis, sperm release, or mature sperm function, resulting in products with a wide variety of usage patterns, from slow onset to on-demand usage. Contraceptives targeting mature sperm functions could even be taken by both sperm-producing and egg producing people. Challenges of non-hormonal contraceptive development include bioavailability and delivery past the blood-testis barrier.
In clinical trials.
As of 2024[ [update]], the following non-hormonal male contraceptive product is in clinical trials:
In preclinical development.
As of 2024[ [update]], the following non-hormonal male contraceptive products are in preclinical development:
Thermal male contraception.
Prolonged testicular heating had been shown to reduce sperm counts in 1941, considered as a method of birth control after 1968 and in the 1980s No modern clinical trials have demonstrated the safety, contraceptive effectiveness, or reversibility of this approach. Various devices are in early preclinical stages of development, and as of 2017 some approaches have been used by men through self-experimentation. As of 2015, the mechanism by which heating disrupts spermatogenesis was still not fully understood. There have been theoretical concerns that prolonged heating could increase the risk of testicular cancer since the inborn birth defect of cryptorchidism carries a risk of testicular cancer or that heating could damage sperm DNA, resulting in harm to potential offspring.
Methods that block sperm release.
These approaches work by either physically or chemically preventing the emission of sperm during ejaculation, and are likely to be effective on-demand.
Non-hormonal pharmaceutical methods in preclinical and clinical development.
α1-adrenoceptor antagonists and P2X1 antagonists have been shown to inhibit smooth muscle contractions in the vas deferens during ejaculation, and therefore prevent the release of semen and sperm while maintaining the sensation of orgasm. Various molecules in these categories are under consideration as possible on-demand male contraceptives.
Vas-occlusive contraception.
Vas-occlusive contraception is a form of male contraception that blocks sperm transport in the vas deferens, the tubes that carry sperm from the epididymis to the ejaculatory ducts.
Vas-occlusive contraception provides a contraceptive effect through physical blockage of the vas deferens, the duct connecting the epididymis to the urethra. While a vasectomy excises, or removes, a piece of each vas deferens and occludes the remaining open ends of the duct, vas-occlusive methods aim to block the duct while leaving it intact. Vas-occlusive methods generally aim to create long-acting reversible options, through a second procedure that removes the blockage. However, full reversibility remains questionable, since animal and human studies have shown sperm abnormalities, incomplete recovery of sperm parameters, and the development of fertility-impairing antibodies against one's own sperm after blockage removal.
In clinical trials.
As of 2024[ [update]], the following vas-occlusive male contraceptive products are in clinical trials:
In preclinical development.
As of 2024[ [update]], the following vas-occlusive male contraceptive products are in preclinical development:
Barrier methods.
Research into new, more acceptable designs of condoms is ongoing.
Methods that block functions of mature sperm.
These approaches work by blocking functions that mature sperm need in order to reach and fertilize an egg in the female reproductive tract, such as motility, capacitation, semen liquification, or fertilization. Drugs or devices that target mature sperm are likely to be effective on-demand (taken just before intercourse), and could even be delivered either in sperm-producing or egg-producing bodies, leading to unisex contraceptives.
In preclinical development.
As of 2024[ [update]], the following non-hormonal male contraceptive approaches are in preclinical or early development:
Acceptability.
Although some people question whether men would be interested in managing their own contraceptives or whether women would trust their male partners to do so successfully, studies consistently show that men around the world have significant levels of interest in novel forms of male contraception and that women in committed relationships would generally trust their male partners to manage the contraceptive burden in the relationship. Additionally, males participating in various contraceptive clinical trials have reported high satisfaction with the products they were using.
Among men.
Studies on potential uptake indicate that in most countries, more than half of men surveyed would be willing to use a new method of male contraception. Interestingly, some of the highest rates were reported in low-income countries like Nigeria and Bangladesh where 76% of men surveyed indicated that they would be willing to use a new method within the first 12 months that it is available. This is particularly compelling, since it has been estimated that a mere 10% uptake of new male contraceptive methods could avert nearly 40% of unintended pregnancies in Nigeria. Across the world, many young and middle-aged men especially want the ability to control their own fertility, and are not well-served by existing family planning programs.
Although a phase II trial for an injectable male contraceptive was halted in 2011 by an independent data safety monitoring board due likely to rare adverse effects experienced by some participants, leading many popular articles to suggest men could not tolerate side effects similar to those that many women endure on hormonal birth control, in reality more than 80% of the study's male participants stated at the end of the trial that they were satisfied with the contraceptive injection, and would be willing to use the method if it were available. Subsequent hormonal male contraceptive clinical trials have progressed successfully, showing high levels of efficacy and acceptability among the participants.
Among women.
It is sometimes assumed that women won’t trust men to take contraceptives, since women would bear the consequences of a male partner's missed dose or misuse. Of course, male contraceptive options would not have to replace female contraceptives, and in casual sexual encounters both partners may prefer to independently control their own contraceptive methods. On the other hand, some long-term couples might want only one partner to bear the contraceptive burden. Indeed, there is evidence that a large proportion of women in relationships in many countries around the world would trust their partners to take a potential male method, and many women want more male partner involvement in their own reproductive health services. Further, current contraceptive use