Contraception 101

Every method has two numbers

Every method comes with two numbers for how well it works, and it isn’t obvious why there are two. The first is perfect use: what happens when a method is used exactly as intended, every single time, with nothing forgotten and nothing rushed. The second is typical use: what happens to real people over a year, including the missed pill, the late appointment and the condom that went on halfway through.

Both numbers are counted the same way: out of 100 people using the method for a year, how many become pregnant. For the combined pill, the perfect-use figure is 0.3 and the typical-use figure is 7. For the external condom, it’s 2 and 13. For withdrawal, it’s 4 and 20.

To put those in context, the number for using nothing at all is 85.

The gap is the whole story

The perfect-use figures are the ones that end up on packaging and in conversation, and they describe a life almost nobody lives. The most careful estimate of what actually happens, from a large survey in the United States, put the pill at about 7 pregnancies per 100 people over a year and the condom at about 13.

The World Health Organization also publishes international figures, and they differ a little, lower for some methods and higher for others. Some of that difference is real, and some of it is how differently countries report these things. The shape holds everywhere, which is the part that matters: the gap is widest for the methods that ask the most of you.

If a method has ever failed you, know this: what the gap measures isn’t carelessness. It’s the distance between a method that asks something of you every day, or every time, and one that doesn’t.

One more thing belongs here rather than later, because this article is written as though the decision happens calmly in advance. If you’ve missed a pill, a condom has failed or an injection is late, go to part five now. Emergency contraception works better the sooner it’s used, and every one of the three options has a window measured in days, not weeks.

Circumstance matters more than the method

This is the finding that almost never makes it into the appointment, and it changes how you read the whole table. The same method fails at very different rates depending on the life it’s used in.

In that US survey, the condom failed about four times as often for women living with a partner they weren’t married to as for married women. The pill failed more than three times as often for women with two or more children as for women who had never given birth. And across all the reversible methods, failure was almost three times as common for women in households below the poverty line as for women in households well above it.

None of that is about chemistry. It’s about how much room a life leaves for doing something correctly every day, and a full life leaves less of that room. The useful question when choosing isn’t which method is best, but which one asks the least of you.

The methods with nothing to get wrong

Look down the table and a pattern appears. The implant, the hormonal coil and the copper coil each have two numbers that are almost identical, all under 1 in 100. Once they’re in place, there’s nothing left for anyone to remember.

The injection shows what happens when a little remembering is added back in. Used perfectly, it’s 0.2 in 100. As people actually use it, it’s 4, a twentyfold difference that comes entirely from appointments that slip.

That’s why these long-acting methods sit in a category of their own. In the US survey, the pill failed about five times as often as the implant and the coils together. It isn’t that they’re cleverer. It’s that they don’t depend on you!

Three places to interrupt

If you’ve ever wondered what your contraception is actually doing, it helps to start with what has to happen for a pregnancy to begin. An egg has to be released. Sperm have to reach it. The two have to meet, and what results has to settle into the lining of the uterus. Every method interrupts one or more of those steps, and knowing which one explains most of what a method feels like to use.

There are three ways in: stop the egg being released, stop the sperm getting through, or make the meeting and the settling far less likely. Most methods do more than one.

The methods that stop ovulation

The combined pill, the patch and the vaginal ring all work the same way. They act on the signals between the brain and the ovaries, turning down the two hormones that make an egg grow and be released, so no egg is released at all. Stopping ovulation is the main way they work, and changes to the cervical mucus, the lining of the uterus and the fallopian tubes add to it.

The injection and the implant do the same thing by a different route, using a progestogenprogestogenThe general name for the synthetic hormones related to progesterone that are used in contraception. Different ones behave differently, which is why two pills that look alike can carry different risks. alone to stop ovulation and thicken the cervical mucus.

The progestogen-only pill is where it gets interesting, because there are two kinds, and they don’t work the same way. The newer ones, containing desogestrel or drospirenone, reliably stop ovulation. The older ones, containing levonorgestrel or norethisterone, affect the hormones but don’t reliably stop ovulation at all. They rely instead on the cervical mucus, a thinner lining and the movement of the fallopian tubes.

That makes a real, practical difference to your day. Under UK guidance, a traditional progestogen-only pill still protects you if you take it within about three hours of your usual time. A desogestrel pill allows twelve hours, and a drospirenone pill allows twenty-four. They’re the same kind of medicine, with an eightfold difference in how much margin you have. The exact window is set for each product and can differ between countries, so the leaflet in your own packet is the one that counts.

Mucus is doing more work than anyone mentions

The mucus made by the cervix changes across a normal cycle, becoming clear and stretchy around ovulation so that sperm can pass. Progestogens turn it into something else entirely: there’s less of it, it’s much thicker, and its structure changes so that sperm struggle to get through to the uterus and beyond.

Thicker mucus is the quiet backbone of most hormonal contraception. It’s what the older progestogen-only pill relies on almost entirely, what the hormonal coil relies on most, and what’s still working in the background of every method that also stops ovulation.

The two coils are not the same device

They’re both small, both fitted through the cervix, and both last for years, which is about where the similarity ends.

The hormonal coil releases a progestogen right where it’s needed. It works on the cervical mucus, which stops sperm getting into the uterus, and on the lining, where it may prevent implantation. Having a device in the uterus may help too, and in some people it stops ovulation, although it isn’t relied on for that. It starts working seven days after it’s fitted.

The copper coil has no hormones at all, and it works straight away. Copper is toxic to sperm and to eggs, and copper in the cervical mucus also stops sperm getting through. It has a second effect too: an inflammatory response in the lining that could make implantation harder.

You might be wondering whether a coil works by ending a pregnancy. That’s the question people actually want answered, and the UK guidelines answer it carefully in both directions. The copper coil has effects both before and after fertilization, but the main way both coils work is by acting before fertilization. A review of the biological evidence put it more bluntly: the common belief that coils work by destroying embryos in the uterus isn’t supported by the evidence.

What the evidence can’t do is say exactly how the two effects divide up. If this matters to you for reasons that aren’t medical, that’s where the evidence stands, and the UK guideline says anyone who raises it should be told what is known and what is uncertain.

Barriers, withdrawal and timing

The rest of the methods work in the simplest way there is: they keep sperm and egg apart, or they avoid the days when the two could meet.

Condoms, internal and external, stop sperm getting in. A diaphragm or cap covers the cervix and is used with spermicidespermicideA gel, foam or film that kills or immobilizes sperm. Used on its own it is one of the least effective methods; it is also used together with a diaphragm or cap.. Withdrawal stops sperm entering the vagina at all, and it works better than its reputation when it’s done perfectly, at 4 in 100, and much worse in everyday life, at 20.

Fertility awareness methods find the fertile days, either by watching the body’s own signs or by counting the days of the cycle. Of all the kinds of method, fertility awareness varies the most. It runs from under 1 in 100 when the most careful sign-based method is used perfectly, to more than 20 in 100 in everyday use for one of the mucus-based ones.

If you track your cycle to avoid pregnancy, this is the part to know. The reason is in the first article in this series: the fertile window moves when ovulation moves, and ovulation moves more than most people were taught.

Bleeding changes, and it is a common reason people stop

If your periods changed after you started a method and nobody warned you, you’re far from the only one. Almost every hormonal method changes bleeding, and what it changes it into depends on the method. It’s worth knowing before you start rather than after, because a change you were told about is a very different experience from one you weren’t.

On the combined pill, patch or ring, up to one in five people have irregular bleeding in the first three months, and it usually settles. The UK guideline also notes that bleeding between periods on the combined pill isn’t very different from what women who aren’t using it report anyway.

On the progestogen-only pill, bleeding is unpredictable and may not settle with time. After a year on the desogestrel kind, about half of people have no bleeding or only occasional bleeding, around four in ten have a regular pattern, and a smaller number bleed often or for more than two weeks at a time.

On the injection, around half or more have no periods at all by the end of the first year.

On the implant, the first three months are broadly a preview of what follows. The pattern varies a lot: roughly two in ten have no bleeding, some bleed only now and then, and others bleed often or for long stretches, at unpredictable times.

The hormonal coil reduces bleeding the most, by up to 90% over a year. By three years, about a quarter of people using the larger device have no periods at all, and about one in eight using the smaller, lower-dose version.

That’s worth pausing on, because it’s why the hormonal coil is more than a contraceptive. If your periods are heavy, UK guidance treats it as the first thing to try, ahead of the combined pill.

The copper coil goes the other way. Periods can be heavier, longer or more painful than before, and there can be bleeding between them. The heavier bleeding often settles with time, but the bleeding in between is less likely to.

Mood is the question people most want answered

If you’ve ever felt low after starting a method and wondered whether it was the pill or just life, you probably want a clear answer. This is also where the gap between what people believe, what studies show and what it means for any one person is widest, so it’s worth going slowly.

The study most people have heard about followed over a million women for several years. Compared with women who weren’t using hormonal contraception, those who were using it were more likely to start an antidepressant for the first time. The increase ranged from about a quarter for the combined pill to double for the patch, and for girls aged 15 to 19 it was considerably higher. The risk peaked about six months after starting, and the authors’ own conclusion was careful to call depression a potential side effect.

Then come the qualifiers, and they matter.

A second large study, of more than 800,000 women, found the same link overall, and then split it by age. In teenage girls it was strong. In adult women it was, in the authors’ words, non-existent.

That study also reported the absolute risk, which the first one didn’t. About 4% of people using hormonal contraception, at any age, were prescribed a medicine for their mental health over the year. And when the researchers tested how well knowing that someone used hormonal contraception predicted whether they’d be prescribed one, the answer was barely at all. They concluded that we need to look for other explanations for the poor mental health of young girls, because this one doesn’t carry the weight.

Meanwhile, four large studies that used depression questionnaires rather than prescription records found no increase in depression on combined methods. A randomized trialrandomized trialA study in which people are assigned to one treatment or another by chance, so that the groups differ only in what they were given. It is the design that can show cause rather than association. that gave women either a standard combined pill or a placebo for three months found a modest drop in general well-being and no difference in depressive symptoms.

A systematic reviewsystematic reviewA study that searches for every piece of research on a question, using set rules, and weighs up what it shows as a whole. of progestogen-only methods found very little link at all.

The UK guideline’s summary is the fairest one there is: some people may experience negative mood changes on combined hormonal contraception, but there isn’t clear, consistent evidence that it causes depression.

What dose does, and what to do about it

One more study is worth knowing, because it asks a better question than most. Instead of asking whether hormones affect mood, it asked whether the amount matters.

It looked at women having a hormonal coil fitted for the first time, and at how many of them started an antidepressant afterwards. The study compared three coils with different doses, and the lower the dose, the fewer new antidepressant prescriptions there were. Once the comparison was adjusted, the two lower doses came out about 15 to 23% below the highest. It was the same hormone, by the same route, in a different amount, and there was a measurable difference.

It’s one study, in women aged 15 to 34 who hadn’t given birth and didn’t have the conditions a coil is often fitted for, so it’s narrower than it sounds. It’s still the best answer there is to a question the public conversation rarely thinks to ask.

So hormonal contraception isn’t simply safe or simply risky for your mood. Which method you’re on may matter more than whether it contains hormones at all.

None of this is a reason to avoid hormonal contraception altogether. If you already live with depression, no method of contraception is closed to you. The World Health Organization places the combined pill, the patch, the ring and both coils in its least restrictive category for depression, noting that the combined pill didn’t increase depressive symptoms in women who already had depression.

The most alarming figure in this research comes from the same group behind the first study. They reported that current and recent users were about twice as likely to attempt suicide. For suicide itself, their estimate was about three times as likely, but it rested on a fairly small number of deaths, and the possible range ran from about one and a third times to about seven times, which means the data can’t pin the number down. Other researchers have formally challenged the methods in print, and of the earlier studies, one found a link and four found none. It deserves to be known, and it doesn’t deserve to be quoted as a settled fact.

A newer and larger study, from Sweden in late 2025, fits that cautious reading. It followed more than two million women and found no extra overall risk of suicidal behavior for pills or for combined methods that are not swallowed. It did find a small rise, about 17% in relative terms, for progestogen-only methods that are not swallowed. It also found a rise among 15 to 18 year olds using pills or combined methods that are not swallowed, which adults did not show. It is still observational, so it can’t show that the hormones caused it.

What it does deserve is a plain response. If you are having thoughts of harming yourself, that is not something to sit with until the next appointment, whatever set it off. Almost every country has a free, confidential line. The first thing to do is tell someone, not stop your contraception.

Weight gain is the most believed and the least supported

If you’ve been told the pill will make you put on weight, that’s what almost everyone expects. The evidence has looked hard for it and hasn’t found a general effect.

A Cochrane review of trials of combined methods concluded that the evidence wasn’t enough to determine whether there’s an effect, but that no large effect was evident, and the few trials that compared the method with a placebo or no treatment found no sign that it caused weight gain. A second review, of progestogen-only methods, found that in most studies the groups didn’t differ significantly, and that average weight gain at six or twelve months was usually under 2 kilograms.

The exception is the injection, where a real difference keeps appearing. In one study, people using it gained around 2 to 3 kilograms more than people using the copper coil, at one, two and three years. But the reviewers rated more than half the studies as low quality, and the studies showing this weren’t randomized, so they can’t separate the method from the people who choose it.

Two more things belong with that. Most of these figures come from six or twelve months. In the studies that ran for several years, the average gain by two to four years was roughly double the one-year figure, although the groups still generally didn’t differ from each other. And the reviewers who found no general effect still recommend that people be told what weight gain is typical.

So the accurate answer isn’t that hormonal contraception never affects weight. It’s that when researchers have gone looking for a general effect, they haven’t found one, that the one place a signal keeps appearing is the injection, and that if you’ve gained weight over several years on a method, nothing here says you’re imagining it.

Desire is more mixed than either side claims

If your sex drive has changed since you started the pill, it’s natural to wonder whether the two are connected. The evidence is more mixed than a simple yes or no.

A large systematic review found that among combined pill users, 85% reported an increase or no change in desire and 15% reported a decrease. A steady decline showed up only with the lowest-dose pills, those containing 15 micrograms of ethinylestradiolethinylestradiolThe synthetic estrogen in most combined pills. The figure in micrograms is the dose, and it is the number that changes between one combined pill and another..

There’s a tidy explanation often offered for this, which is that the pill lowers free testosterone. It’s less tidy than it sounds. A meta-analysismeta-analysisA study of studies: it pools the results of many studies on the same question to estimate how large an effect usually is, rather than relying on any single result. that looked at whether a woman’s own testosterone level predicts her desire found a moderate link overall, and the link was the same whether or not the women were using hormonal contraception.

The UK guideline calls the evidence mixed and limited, notes that most studies had no placebo group, and says there’s no clear evidence of a link with the standard 20 microgram pill. It also records the findings that point the other way: desire may be lower on pills below 20 micrograms than on those at 20, and one small trial found lower desire and arousal scores in women randomly given the pill than in women given barrier methods. The UK’s national health service puts it more flatly, saying there’s no evidence that the pill changes your sex drive.

All of that fits with about 15 in 100 people noticing a drop, which is the number worth carrying. If you’re one of them, it’s worth raising with whoever prescribed it.

What happens when you stop

If you might want a baby one day, this is probably the question underneath all the others. A meta-analysis found that about 83 out of 100 women became pregnant within twelve months of stopping contraception, with no significant difference between hormonal methods and the coil. Neither the type of progestogen nor how long someone had used the pill made a significant difference.

A wider review found similar rates after the pill, the coils and the implant, and no increase in pregnancy complications or other problems after stopping any reversible method.

The World Health Organization puts it most clearly: of all contraceptive methods, only sterilization is permanent, and no other method causes permanent infertility.

There’s one real exception to how quickly things return, and it’s the injection. It can take up to a year for ovulation to come back after stopping it. That’s an outer limit rather than a typical wait, and it’s a delay in ovulation returning, not a loss of fertility afterwards. If you want to be pregnant within the year, it’s a reason to choose something else.

Clots, written out

Of all the risks of the combined pill, clots are the one you’ve most likely heard about. The medical name is venous thromboembolism, a blood clot forming in a vein. On its own, the relative figure sounds alarming: the combined pill roughly triples the risk. The actual numbers are what turn that into something you can weigh.

In a year, among 10,000 women who aren’t pregnant and aren’t using combined hormonal contraception, about 2 will have a clot.

That starting figure is itself uncertain, and the UK guideline says so. Other estimates put it higher, somewhere between about 4 and 10 in 10,000. The comparisons below use the lowest figure, which makes them the least flattering version.

Among 10,000 women using a pill containing levonorgestrel, norethisterone or norgestimate, about 5 to 7 will have a clot. With etonogestrel or norelgestromin, it’s about 6 to 12. With drospirenone, gestodene or desogestrel, it’s about 9 to 12.

Two things follow from those numbers. The first is that which pill you’re on genuinely matters, and it’s a reasonable thing to ask about. The second is that the difference between the highest and lowest rows is about five clots per 10,000 women a year, which is a real difference and a small one.

Of the clots that do happen during use, around 1% are fatal. The guideline’s own summary is the right one: the risk is increased, and the absolute risk for any individual remains very small. It’s also lower on the pill than during pregnancy and the weeks after giving birth, which is the comparison that most often gets left out.

Which is exactly why breaks are a bad idea

You may have heard that it’s good to give your body a break from the pill now and then. The risk of a clot isn’t spread evenly across the years, though. It’s highest in the first months after starting, and after restarting following a break of a month or more. It falls across the first year and then stays flat.

That one fact undoes a very common piece of advice. A break doesn’t let your body recover from a risk that builds up; it re-runs the riskiest part. The guideline puts it plainly: for eligible women under 50 there’s no arbitrary limit on how long the combined pill can be used, and repeated starting and stopping should be discouraged.

Cancer, over a lifetime rather than a year

This is the risk people worry about most and understand least, partly because the answer genuinely goes in both directions.

The best evidence comes from a British study that recruited tens of thousands of women and followed some of them for more than 40 years. Having ever used the pill was linked with lower rates of bowel cancer, cancer of the lining of the uterus, ovarian cancer, and cancers of the lymph and blood-forming systems.

It was also linked with higher rates of breast and cervical cancer, but only in current and recent users, and that increase seemed to disappear within about five years of stopping. The UK’s health service is more cautious, saying the risk returns to normal within ten years. A raised rate of lung cancer showed up too, but only in women who were smokers when they joined the study.

The researchers’ conclusion was that for past users, the overall balance of cancer risk was neutral, with the increases balanced out by reductions that last for at least 30 years.

For ovarian cancer in particular, a large pooled analysis found that the longer the pill was used, the lower the risk, and the protection faded only slowly, still present 30 years after stopping. In high-income countries, ten years of use was estimated to lower the chance of ovarian cancer before the age of 75 from 1.2 in 100 women to 0.8.

The British study began when pills contained far more hormone than they do now, which is worth remembering in both directions.

One newer finding concerns the progestogens in hormonal birth control. Meningioma is an uncommon brain tumor, usually benign and slow growing, though it can press on the brain and sometimes needs surgery. Studies from France (2024 and 2025) and Denmark (published July 2026) found a higher chance of meningioma among women using some progestogens. It was clearest for the injection. The French studies also found it for the desogestrel mini pill after long use. The Danish study added several combined pills and the 52 mg hormonal coil, but found no clear rise for pills with norethisterone or norgestimate, the norethisterone mini pill or the lower-dose coils.

The absolute risk is still low, and it rises with age. For women aged 45 to 49, the Danish figures work out at roughly one extra case a year for every 20,000 to 40,000 women using one of those pills or the 52 mg coil, and for about every 4,300 using the injection. The studies do not all agree: the French ones found no rise for the 52 mg coil or for levonorgestrel pills. The link was strongest in current or recent users and, for most methods, no longer apparent after about five years.

If you have, or have ever had, a meningioma, tell whoever prescribes your method. The UK’s College of Sexual and Reproductive Healthcare advises against the injection and desogestrel pills in that case, and says the implant may not be appropriate. For everyone else, it advises weighing the small extra risk against the benefits of contraception, including preventing an unplanned pregnancy.

Three options, and most people are offered one

If you’re reading this the morning after a condom split or a pill was missed, it makes sense to feel panicky. You have more options than most people are offered, and the sooner you act, the better they work.

There are three things that work after sex: a copper coil, and two different pills, levonorgestrel (sold as Plan B in the US and Levonelle in the UK, among other names) and ulipristal (ellaOne, or ella in the US). They aren’t interchangeable, they don’t work for the same length of time, and the one the UK guideline ranks first is the one people are least likely to ask for by name.

The two pills share a limit that’s rarely explained. They work by delaying or preventing ovulation. Once ovulation has happened, the pills don’t work at all. The copper coil is the exception, and that’s why the order of this section matters.

The copper coil is the most effective, and the least asked for

Fitted as emergency contraception, the copper coil has a pregnancy rate below 1 in 1,000, far lower than either pill. It’s the only option that still works after ovulation has happened. It can be fitted within five days of the first unprotected sex in a cycle, or within five days of the earliest likely day of ovulation, whichever is later. In a regular 28-day cycle, that means up to about day 19.

Your weight isn’t known to affect it, although a higher body mass index does raise the chance of the device being pushed out afterwards, which is worth knowing so you can check. And it carries on working as contraception, so one appointment covers both the emergency and the next several years.

The guideline’s recommendation could hardly be stronger: it says the copper coil should be considered by all women who have had unprotected sex and don’t want to become pregnant. It’s worth knowing that, because it’s something you can ask for!

The two pills are not the same pill

Whichever pill you take, take it as soon as you can. Nothing below changes that, and the time limits are outer limits, not deadlines to use up.

Ulipristal acetate delays ovulation for at least five days, which is long enough for sperm from that time to stop being able to fertilize an egg. It works for up to 120 hours, or five days, after sex, and its overall pregnancy rate is reported at about 1 to 2%.

Levonorgestrel is licensed for up to 72 hours, or three days, and the evidence suggests it doesn’t work after 96. It delays ovulation only if it’s taken before the hormone surge that triggers ovulation has started, which ulipristal doesn’t depend on. Its reported pregnancy rates run from 0.6 to 2.6%.

In the trial that compared the two directly, ulipristal had fewer pregnancies among women treated within three days, but the difference only became statistically significant when pooled with earlier data, in an analysis funded by the company that makes ulipristal. What stood out more was the later window: among the women treated between three and five days after sex, three became pregnant, and all three had taken levonorgestrel.

As for how many pregnancies each one prevents, ulipristal is estimated at around 60 to 80%. The older claim that levonorgestrel prevents about 85% hasn’t held up well, and a more recent estimate puts it at 69%.

Two practical notes rarely get said out loud. If you take ulipristal, guidelines advise waiting five days before starting or restarting hormonal contraception, because starting sooner works against the ulipristal you’ve just taken. And if you’re breastfeeding, either pill is fine: UK guidance changed in 2025, and there’s no longer any need to pause breastfeeding after a single dose of ulipristal.

Weight can change the answer

Your weight can change which emergency pill works best.

The UK guideline is explicit: levonorgestrel could work less well above a body mass index of 26, or a weight over 70 kilograms, and in that situation either ulipristal or a double dose of levonorgestrel should be given. It adds that it isn’t known which of those two is better. The threshold you’re given depends on where you are. The World Health Organization and US guidance use a body mass index of 30 rather than 26, so the same person can be told two different things in two countries.

Ulipristal isn’t exempt either. A meta-analysis found it less effective above a body mass index of 30 than below it.

A standard single dose of levonorgestrel is the easiest thing for a pharmacy to hand over, and none of this comes with it unless somebody asks. If you’re near either line, say so and ask.

It is not an abortion pill

If you’re worried that taking emergency contraception means having an abortion, it doesn’t. The World Health Organization states it directly: emergency contraceptive pills work by preventing or delaying ovulation, and they don’t work if a woman is already pregnant. If they’re taken during a pregnancy nobody knew about, there’s no known harm to the woman, to the pregnancy or to the fetus.

The copper coil, fitted for emergency use, goes in well before the earliest point at which a pregnancy could implant, which is six days after ovulation at the very soonest, and usually eight to ten.

The UK guideline also says something worth repeating: if this matters to you, you can ask, and you should be told what is known and what is uncertain.

The day matters more than the hour

The effectiveness figures you’ll see for emergency contraception are strange numbers, and the guideline says so. If a study gives a pill to everyone who came within three days and 1% become pregnant, that 1% includes a great many women who were nowhere near ovulating and were never going to conceive that time.

As the guideline puts it, for a woman who had unprotected sex just before she was likely to ovulate, it would be inappropriate to tell her she has only a 1% chance of pregnancy. Her risk is higher, and the choice of method matters more, precisely because she’s in the part of the cycle where it counts.

That’s the practical takeaway. Where you are in your cycle changes what to ask for, and it’s the first thing worth saying when you ask.

Two methods, and one of them is permanent

If you’re a man reading this, you might have noticed how little of it has been about you. Half of the people involved in any pregnancy are men, and apart from withdrawal, the options available to them are a barrier and an operation. That’s the whole list, and it has been the whole list for a long time.

Condoms have a perfect-use figure of 2 in 100 and a typical-use figure of 13. The gap is the same story as everywhere else: something that has to be done correctly every time, by someone, in the moment.

For infections, condoms are the only thing on this page that does anything. Using them consistently is estimated to cut HIV transmission from a partner who has it by around 80% in heterosexual couples, and the US Centers for Disease Control and Prevention notes that this is probably an underestimate, because it depends on people reporting their own use accurately.

Vasectomy is more effective and less risky than the female equivalent

This comparison isn’t widely known, and it’s a striking one. The UK guideline states that vasectomy has a lower failure rate and less risk than female sterilization done by keyhole or open surgery.

Once a semen test has confirmed the operation worked, about 1 in 2,000 vasectomies fail. For tubal sterilization by keyhole surgery, the lifetime failure rate is estimated at about 1 in 200.

Those aren’t the same numbers as the ones in the table in part one, which put vasectomy at 0.15% and tubal surgery at 0.5% over the first year. They don’t conflict. The table counts everything that happens in the first twelve months, including pregnancies before a semen test has confirmed anything, while the guideline’s figure is the long-run risk once it has.

The part that’s easy to get wrong is the waiting. A vasectomy doesn’t work straight away, and you’ll need another method until a semen test confirms that it has. Sperm already past the point of the operation take time to clear, and the guideline puts the best time for the first semen test at twelve weeks. Pregnancies have happened years afterwards, which is rare, and it does happen.

It isn’t free of consequences either. The guideline names a risk of pain in the testicles, scrotum, penis or lower abdomen afterwards, which is rarely severe and in some men is long-lasting.

Why there is still no male pill

If you’ve wondered why there’s still no pill for men, it isn’t for lack of trying, and the most advanced trial was stopped early for a reason that connects directly to part three.

In that trial, men were given an injection combining a progestogen and testosterone every eight weeks. It worked. In almost all of the men who kept going, sperm counts fell to the target level, the pregnancy rate among their partners was about 1.6 per 100, and nearly all of them had normal sperm production back a year after stopping.

The authors called that relatively good compared with the other reversible methods available to men, which is the right comparison and a lower bar than the table in part one. About 1.6 per 100 is better than the pill as people actually use it, but it’s about five times the pill’s perfect-use figure and many times the implant’s.

The trial was stopped early, on the advice of an outside safety committee, because of side effects. The most common were acne, pain where the injection went in, increased libido, and mood changes. The authors noted that mild to moderate mood changes were relatively common, and that is the same side effect part three looked at for women, where the evidence is still debated.

Work continues. A hormonal gel combining segesterone acetate and testosterone has been tested in a large phase two trialphase two trialThe middle stage of testing a drug: a few hundred people, enough to show whether it works and at what dose, before the much larger trials that decide whether it is approved., and another compound is in trials too. But as of now, no reversible hormonal method for men is on sale anywhere, and no full results from that gel trial have yet appeared in a medical journal.

There’s also a practical obstacle that rarely gets mentioned: in 5 to 10% of men, the hormonal approach doesn’t bring sperm production down enough.