If you have ovaries and a uterus,  chances are you’ve heard about menopause.

But that’s something that happens  to older people, right? Not you.

Well, it turns out that menstruation’s  curtain call might start much earlier than you realize,  and it lasts longer, too. [♪ INTRO] Whether you're trying to avoid pregnancy  or just understand what’s happening with your body, figuring out when the heck  menopause is coming can be really useful. And the first hint that menopause might  be on the horizon is declining fertility. That typically starts around age 35.

Not 50. It’s absolutely still possible to have a baby, but this is when it gets  harder for a lot of people. People who are under 30 have an 85%  chance of conceiving within a year, which drops to 75% by 30, 66% by age 35,  and all the way down to 44% at age 40.

Declining fertility starts with your ovaries. If you think way back to health class,  you might remember that humans are born with all the immature eggs, or oocytes,  they’ll ever have in their lifetime. That’s around a million at birth, which  declines to half a million by puberty.

And by age 37, there’s only 25,000 oocytes left. Ovaries are filled with  tiny sacs called follicles. And each follicle is pretty  much a cocoon for an oocyte.

And every month, a handful of these follicles are chosen to work on maturing their egg. But during ovulation, usually only one  dominant follicle gets to release its egg, which will travel down the fallopian tube. And you know how the rest of the story goes.

So even though only one egg goes down  the tube, all those other follicles that were under construction also get lost,  in a process called follicular atresia. Those follicles didn’t make the cut, so they get reabsorbed, and those eggs are gone. That means every month during  your reproductive years, you’re losing a good number of eggs, which is one reason for  declining fertility as you age.

So the first step toward menopause  is a decrease in fertility. And with time, that decrease in  fertility from the follicle loss will start to cause symptoms and  even mess with your menstrual cycle. Menstrual cycles are a lot more complicated  than you’d think, as it turns out.

It’s not just a little alarm  clock that goes off and says “hey, time to feel terrible for a few days!” Cells in the follicles called granulosa cells make hormones like estradiol, a type of estrogen. In a typical menstrual cycle,  estradiol peaks before ovulation, which causes the brain to release  gonadotropin releasing hormone, which then causes the pituitary  gland to release luteinizing hormone. That spike in luteinizing hormone  is what tells your body to ovulate.

So fewer follicles means less estrogen, which could make you miss that  spike altogether, so no ovulation. Or your body could try and compensate and you could end up bleeding more frequently. Either way, this is the start  of what’s called perimenopause, which is essentially the 1-10 years of declining fertility immediately before menopause.

At some point you cross that threshold of  too few follicles to maintain a typical menstrual cycle, and that’s when you  can start to have some whacky cycles. You might have more frequent menstruation,  a missed ovulation here or there, longer cycles, missed cycles,  and eventually no cycles. All of that falls under perimenopause,  and beyond having fewer and older eggs than ever, the variation you start to see in  your cycle also means decreased fertility.

Because at that point, you  have a moving, shrinking, and intermittently absent dart board. Everyone is born with a  different number of follicles, and people lose them at different  rates too, which might be partially why there’s so much variation in  menopause and perimenopause onset. The average age of menopause in the US is 51, but it can happen anywhere from 40 to 60.

You’ll know you’ve hit menopause when you go 12 months straight without a period. Before then, if you’re trying not to get  pregnant, regardless of fertility declines, you could still conceive, so  the official recommendation is to use contraception until  you officially reach menopause. But if you’re using something like an  IUD and don’t get periods normally, figuring out when you’ve  reached menopause can be tricky.

So the pros recommend to keep  using contraceptives until age 55. Variations in perimenopause and full-on menopause means lots of differences in onset and duration. Like, for example, maybe a person’s  fertility started dipping in their thirties, and perimenopause didn’t start until 45 and then they entered menopause soon after at 47.

Meanwhile another person could  have had their last child in their late thirties and then started  perimenopause at 47 and menopause at 57. Everybody’s bodies are different, so even decades of variation can be totally normal. And then there’s the less normal variation too.

Menopause is considered early if  it starts before the age of 45, and premature if it’s before 40. Some people even go through menopause  in their 20s, though that’s very rare. Since for some people perimenopause  starts younger or lasts longer, the age where it probably ends  up on your radar is around 35.

That’s when they slap you with  the very attractive title of geriatric pregnancy too,  although recently it’s been more politely renamed as advanced maternal age. It’s important to note that people of all  sexes can have age-related fertility issues. This video is about menopause, but  “Man-opause” isn’t total fiction either.

As males age, their testosterone levels  begin to fall around 1% each year, though that varies based on  things like obesity or stress. It’s called andropause, but it isn’t  super noticeable like menopause can be. A lot of people can have these decreases but still have normal testosterone levels,  or they can be totally asymptomatic.

This usually starts in your 30s, but  again, this can vary for lots of people. So, fertility decreases with age, and those decreases can get on  anyone's radar, regardless of sex. With that timeframe ironed out, here’s what you can expect from  perimenopause and into menopause.

First, let’s talk periods. You may first notice irregular cycles,  then the occasional skipped period, and toward the end, you can go  multiple months without a period. The final step is full-on menopause,  which means no period for a full year.

More on that in a minute. Just a heads up, we’re about  to talk about miscarriages. If that is something you’d rather not hear today, you can skip to this timestamp on screen.

Perimenopause also comes with an  increased chance of miscarriages, also known as spontaneous abortions. Under 30, people have about  a 10% chance of miscarriage. That climbs to about 20% by age 38, 30%  at 41, and over 50% chance by age 45.

The older an oocyte gets, the more  likely it is that the DNA inside can break down or even duplicate when it shouldn’t. So when that egg meets sperm, degraded DNA can increase  the odds of misalignments, leading to increased chances of  genetic conditions and miscarriages. Older sperm can have mutations that  contribute to miscarriages too.

And, in general, older eggs and  sperm, are also associated with an increase in birth defects, stillbirth,  gestational diabetes, and other complications. Another symptom is hot flashes, which can affect up to 85% of menopausal people. On average they last just under a decade, though around a third of menopausal  people will have them even longer.

Lower estrogen levels may cause  increased core temperatures and narrower tolerable temperatures,  though other research suggests that altered serotonin levels may be  what’s changing the thermostat. Sleep problems also become a major problem during perimenopause and menopause. Some of that could be chalked up to your  run of the mill age-related insomnia, but menopause seems like it might make it worse.

The night sweats probably don’t help with sleep, and when you add in the increased rates  of stuff like anxiety and depression, it all adds up to fewer Zs. That risk of depression is a big one. Some studies show that you’re  three to four times more likely to have a depressive  episode during perimenopause.

And that makes sense because most of the symptoms of perimenopause are neurological. No, that doesn’t mean it’s all in your head. I mean there are literally  changes happening in your brain.

Estrogen plays a role in regulating  a ton of stuff in the brain, from thermoregulation to sleep to memory, so changes in estrogen can  send any of that into chaos. Another of the not so pleasurable  side effects is painful sex, also called dyspareunia. Essentially, less estrogen causes changes  in the urinary and vaginal tracts, leading to vaginal dryness, pain  during sex, or urinary incontinence.

And unfortunately those can be permanent  without some type of treatment. So let’s talk treatment. But before we get to that,  here’s a quick ad break.

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You can find them all to try for  free at brilliant.org/scishow, by scanning the QR code onscreen, or clicking  on the link in the video description. And you’ll get 20% off an  annual premium subscription. The goal of treatment during menopause  isn’t to prevent or reverse fertility loss, but to make the transition a bit less… miserable.

Especially for those who have  severe or long lasting symptoms. Which is where hormone replacement  therapy, or HRT, comes in. This is usually a combination  of estrogen or progesterone, and can be prescribed to help  with things like hot flashes, night sweats, vaginal dryness, and sleep troubles.

A 2023 phase 3 clinical trial on  progesterone pills found that even though the pills didn’t lead to fewer hot  flashes or better sleep quality, the participants felt that both of those  things improved by the end of the trial. Higher levels of estrogen are linked  to higher cognitive performance, and some studies suggest that estrogen  supplements during perimenopause can decrease your risk of Alzheimer’s disease, although we still don’t 100% know why. One 2009 study found that  it’s important to start HRT before your last menstrual cycle in  order to get the cognitive benefits.

But the symptoms of perimenopause and  menopause aren’t caused by estrogen alone, meaning estrogen-based HRT might  not get the job done for everybody. Fortunately, there’s another kind of  hormone therapy that may help: testosterone. Adding testosterone to the mix seems to address the sex related concerns for some people.

See, your ovaries don’t just make  estrogen, they also make testosterone. And when the ovaries wind down on the estrogen, they secrete less testosterone too. And since there are testosterone  receptors in our brains and genitals, adding a boost of T seems to help address some of the sex-related symptoms of menopause.

A 2019 meta-analysis found that taking  testosterone treatment after menopause could address a wide array of sexual dysfunction, increasing everything from desire and  self image to pleasure and orgasm. But experts say that testosterone  replacement isn’t for everyone. If you were looking for  relief from pretty much any other menopause symptoms, this isn’t gonna do it.

And it isn’t recommended for people  with heart conditions either. Non-hormonal treatments can  target specific symptoms, like treating anxiety and  depression with antidepressant meds. So how long does menopause last?

Technically, your periods will  be paused the rest of your life. And if you have any unexpected  bleeding after that time, you should get checked out by a  doctor to rule out other problems. After menopause, most doctors say  you’re in what’s called post menopause.

Once you hit that, some of the  menopause symptoms may wane, like hot flashes and night  sweats, while other symptoms, like vaginal dryness, can  persist without treatment. It’s important to keep in  mind that all of this data refers to populations, not individuals. Every person's situation is unique, and  fertility varies greatly not only by age, but from person to person.

And lots of factors outside of  age can affect fertility too, like nutrition, weight, and exercise. So you can think of menopause as  the end of a long, slow process, rather than a thing that just happens all at once. Your 30s may mark a winding  down of the reproductive system, but it doesn’t necessarily mean  the whole shop is closed down.

And knowledge is power, so now  you’ll be ready for whatever your changing hormones might  throw your way. Period! [♪ OUTRO]