BBC Science Focus Magazine
By Holly McHugh
For decades, the responsibility of contraception has largely fallen on women. While birth control is certainly not a bad thing and allows us the sexual freedom we desire, it is not without its downsides. Mood swings, irregular bleeding, tender breasts and several other unwanted side effects are what many women endure in order to prevent pregnancy. Therefore, it is no surprise that ladies (and gents!) are keen for a male contraceptive alternative to level the playing field.
Currently, men have limited options when it comes to contraception, despite a willingness to share the responsibility. They can either use condoms or get a vasectomy, a surgical procedure for permanent male sterilisation. On the other hand, women have many choices that are more reliable than condoms and less permanent than sterilisation: birth control pills, intrauterine devices, patches, implants and injections.
In an attempt to develop a suitable method of contraception for men, scientists have spent years researching male contraceptive pills, but are yet to create an effective one that doesn’t cause unwanted side effects.
Most previously tested pills work by blocking the hormone testosterone to suppress sperm production. The problem with interfering with hormones like this is that it will undoubtedly cause side effects. For example, testosterone blockers cause symptoms like depression, weight gain, liver problems, acne and decreased libido. As a result, no contraceptive pills have made it to the shelves so far.
But now, it appears good things are on the horizon, after a team of eager researchers from the University of Minnesota reported they have developed a new male contraceptive pill. So far, it has proven effective in mouse studies and is set to enter human trials soon.
According to their results presented at the American Chemical Society Spring 2022 meeting, the pill was 99 per cent effective at preventing pregnancy after male mice received the drug orally for just four weeks – the same effectiveness as the current contraceptive pill for women. This is a promising result.
Plus, in even better news, the pill appeared to have no side effects, thanks to the lack of hormones. This remained true even after delivering an overdose of the drug.
So how does it work? Unlike female birth control pills, this new pill contains zero hormones. Instead, it works by blocking a protein from binding to vitamin A, which is essential for sperm production and fertility. Essentially, it causes sterilisation.
This may sound scary, but the researchers found that the sterilising effect of the pill could be totally reversed within four to six weeks of stopping the drug. After this point, male mice were successfully able to sire pups.
However, although this pill is a promising candidate, scientists caution people not to get ahead of themselves. So far, it is only effective in mice and may affect men differently – we are humans after all and work completely differently from rodents.
But given the major positives seen in mouse studies and the absence of hormones, scientists are hopeful this contraceptive pill will remain effective and free of side effects.
If the upcoming human trials are a success, a male contraceptive pill may reach the shelves before we know it. This breakthrough will revolutionise male contraception and allow men the freedom to take control of their own reproductive health.
Women will also no longer have to bear the burden of birth control alone – a win win for everyone.
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