© Bill Binzen
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It's hard to imagine that truly effective contraception/birth control didn't exist until the last century. Preventing unplanned pregnancies indirectly reduces the likelihood of high-risk abortions and high-risk pregnancies. By extending the interval between pregnancies, contraception allows parents to spend more time caring for their young children, increasing the survival rate of young children. However, in the past, the real effective contraceptive methods for men were relatively single, and such as vasectomy, were often irreversible.
Not only that, but while current contraceptive methods are relatively safe and effective, it is often women who suffer from the side effects. So, is there a contraceptive method that can be used by both men and women?
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In the next few decades, a new generation of contraceptives may enter the U.S. market. One is a pill that blocks certain cells from being exposed to vitamin A, which can limit fertility without hormones, and an injection, which temporarily blocks the reproductive system. The method that is progressing most smoothly in the current trial is a topical gel that is applied daily to the shoulders and upper arms to provide temporary contraceptive effect with no effect on mood or libido [1]. Christina Wang, a contraceptive researcher at the Lundquist Institute in California and one of the developers of the gel, told me, "Overall, we didn't find any serious adverse events at all. "The upcoming range of contraceptives is striking not only for its imaginative nature, but also for its target audience: men. For decades, men looking to control their fertility were limited to two imperfect options: condoms or vasectomy. But in recent years, researchers have developed simple, convenient, and effective contraceptive methods for men with almost zero side effects. Soon, women may not be forced to bear the burden of almost all contraception. The upcoming innovations aren't just about expanding contraceptive options for men. Better male contraception would not have emerged without the many scientific paths that had previously been paved for female contraception. Now, it seems like the time has come for women's contraceptive methods – many of which still come with tiresome and sometimes dangerous side effects – to something in return. It is true that the mechanism that prevents the egg from being expelled from the ovaries does not exactly overlap with the mechanism that prevents sperm from entering the female reproductive tract. But in principle, "there are a lot of similarities between them," Diana Blithe, head of the contraception development program at the National Institutes of Health, told me, meaning that research in one area could easily be borrowed from another.
© Joanne Imperio
While focusing on the achievements of contraception for men, researchers may soon be able to offer women new forms of contraception that are not only more tolerable, but also more on-demand, less invasive, and even available on both male and female reproductive systems. In the more than 60 years since birth control pills were first introduced, women's contraceptive options have become diverse. People can choose physical isolation or choose between birth control pills, patches and implants, and they can choose to receive several injections a year or have an intrauterine device implanted with contraception that lasts up to 10 years. "We have so many options, it's like supermarket cereal shelves," Amy Alspaugh, a nurse and reproductive health researcher at the University of Tennessee, Knoxville, told me. Many contraceptive methods are also improving: IUDs, implants and injections now last longer and are easier to place and remove; "In the past, we basically gave a horse a dose of estrogen and progestin," Alspoo told me. Now the dose we give is the lowest dose we know is still effective to reduce side effects. ”
阴道环，可以预防怀孕并降低艾滋病毒风险。 © Population Council
Some researchers have been exploring new methods of contraception, such as microneedling [2] and even microchip technology that allows women to adjust their birth control remotely [3] (the latter of which raises privacy concerns). The Population Council, a New York-based NGO that has been working on a multifunctional vaginal ring, told me that in addition to preventing pregnancy, the ring releases an antiviral drug to protect women from HIV [4]. In general, the changes in female contraceptive methods are mainly gradual – more of a replacement of ingredients than a completely new formulation. Heather Vahdat, executive director of the Men's Contraception Initiative, told me, "Basically, for the last 30 years, we've had pretty much the same choice. ”
宫内节育器（IUDs）。 © Kettering Health
Many women are still unhappy with the inconvenience and risks that come with existing options. Some people experience weight gain, acne and mood swings, or are concerned about the risk of stroke that hormonal contraceptives may bring. Others often experience pain in the process of IUD placement: Manually inserting the device into the lower abdomen without anesthesia may not be acceptable in other contexts, but for female contraception, "we've socialized the process as something acceptable," Brian Nguyen, an obstetrician-gynecologist and contraceptive researcher at the University of Southern California, told me. Non-hormonal measures such as condoms, diaphragms, and spermicidal suppositories, while easy, are generally less effective than hormonal contraception. Waddat told me that women would definitely benefit from more on-demand contraception — that is, using contraception during sex, "not just just in case," which would save them from the side effects of a whole month, an entire year, or even a decade. For years, some researchers have argued that some significant inconveniences and side effects are acceptable for female contraception. After all, women weigh these costs with pregnancy in mind, and pregnancy itself is dangerous and can be accompanied by life-threatening complications, while men use contraception to prevent others from becoming pregnant.
Nestorone，一种男性避孕凝胶。 © Population Council
I asked Wadat if the typical side effects of the female contraceptives currently available would be able to pass the review of any male contraceptive experiments. "Based on history," she told me, "I don't think so." Several other experts agreed. In 2011, a global trial of injectable hormonal contraceptives for men was halted after an independent safety review committee determined that the drug's side effects "outweighed the potential benefits" [5]. The side effects involved include mood swings and depression, both of which are often seen in women who use birth control pills. However, most of the participants who insisted on participating in the trial said they wanted to continue using the injection. In recent years, Nguyen has heard more and more men mention in contraceptive trials that one of the reasons they participated in the trial was their female partner's negative experience with the pill. "A lot of people think that the risk to their partner is the same as the risk to themselves," he said. Strict standards for male contraceptive tolerance have also raised the bar for contraceptive methods for women. This crossover is already underway. Researchers deliberately used natural testosterone and progestogen as ingredients in topical contraceptives for men, and experts told me that the goal was to better mimic the substances naturally found in men's bodies to minimize unwanted side effects. At the same time, many female hormonal contraceptives rely on a synthetic compound called ethinylestradiol, which does not exactly mimic the estrogen produced in a woman's body and may increase the risk of blood clots. The Population Commission is now working on an alternative vaginal ring to replace ethinyl estradiol with hormones that are more biologically appropriate to women. Other conveniences may be more difficult to achieve. For example, researchers hope to one day offer men a more reversible vasectomy procedure, in which a dissolvable or removable hydrogel is implanted into the vas deferens. But experts tell me that it's more difficult to temporarily block the fallopian tubes. In addition, although sperm is constantly produced, the cycle of egg release for fertilization is difficult to measure and predict, which can also lead to side effects that are difficult to control. Targeted interventions on the testicles are also easier to achieve and more likely to be verified than the ovaries: men have long been able to check their sperm counts using devices similar to home COVID tests, but similar testing devices do not exist for women. In addition, Mitchell Creinin, a contraceptive researcher at the University of California, Davis Health, said that because sperm takes months to produce, male hormonal contraceptives may not matter to users who miss a day of use — and many drugs designed for women often don't have that flexibility. However, the difficulty of coping with eggs does not mean limiting a woman's options. Conception only happens when the egg and sperm actually meet, which means that almost any medication designed to hinder sperm function or motility may work in the female reproductive tract. These options go far beyond spermicidal suppositories: the Population Commission is working on a product that can alter vaginal acidity to stop sperm from swimming normally, while Deborah Anderson, an immunologist and reproductive health researcher at Boston University, has been working on a soluble film that contains sperm-blocking antibodies that can be placed into the vagina before sex and appears to provide 24 to 48 hours of contraceptive effect. Some of the drugs being trialed for men may even be available for the female market in the future, including a drug that suppresses sperm motility, and it may also work in the female reproductive tract.
In 2022, a hospital in Melbourne, Australia, is experimenting with an injectable male contraceptive measure in which the hydrogel in the injection can stop sperm from flowing out of the testicles and is said to be valid for up to 2 years. © Epworth HealthCare
With the growing focus on men's contraceptive preferences, some researchers worry that women's needs will be further overlooked. Jeffrey Jensen, a contraceptive researcher at Oregon Health & Science University, told me that while grants for male contraceptive methods continue to be approved, his team has had to suspend work on some female contraceptive programs due to lack of funding in recent years. And Hitruk-Wahl said that although researchers had started working on topical contraceptive gels for women at one point, "sponsors were more interested in gels for men." Allison Merz, an obstetrician-gynecologist at the University of California, San Francisco, told me that the arrival of male contraception is unlikely to dampen women's enthusiasm for using their own contraception. If anything, they're going to spark more discussion about female contraception when these super-safe and effective men's products hit the market: Why didn't convenience and tolerability become a priority for women in the first place?
Bibliography:
[1]www.nichd.nih.gov/newsroom/news/080222-NEST
[2]www.ncbi.nlm.nih.gov/pmc/articles/PMC9000369/
[3]www.cbsnews.com/news/remote-controlled-contraception-on-the-horizon/
[4]www.ncbi.nlm.nih.gov/pmc/articles/PMC3530627/
[5]www.theatlantic.com/health/archive/2016/11/the-different-stakes-of-male-and-female-birth-control/506120/
文/Catherine J. Wu
Translated by tamiya2
Proofreading/Bunny's Limbo microstep
Original/www.theatlantic.com/health/archive/2024/04/birth-control-male-contraception-revolution/677954/
This article is based on a Creative Commons license (BY-NC) and is published by tamiya2 at Leviathan
The views expressed in this article are those of the author and do not necessarily reflect the views of Leviathan
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