Somewhere between the first missed period and the last one, a quiet decision gets made. The cycles have gone strange, the flushes have started, nothing has happened in months, and the condoms stop appearing. Nobody announces it. It just stops feeling necessary.
It is the single most common contraceptive mistake of midlife, and it rests on a confusion worth clearing up: fertility falling is not fertility ending. Perimenopause is not a state of infertility. It is a state of unpredictability, which is a different thing, and in some ways a more dangerous one.
Yes, you can get pregnant in perimenopause, and you can get pregnant while your periods are erratic, while you are having hot flushes, and while you are convinced you are past it.
You are still ovulating, just not to a timetable. Some months you release an egg, some months you do not, and you have no way of telling which kind of month you are in until afterwards. A cycle can arrive after ninety days of nothing. Ovulation precedes the bleed, so by the time you know a cycle happened, the fertile window has already been and gone.
That is the whole problem in one sentence: you cannot use an unpredictable cycle to predict anything.
UK guidance from the Faculty of Sexual and Reproductive Healthcare is specific, and most women have never heard it.
Read the second line again. If your periods stop at 46, you need contraception until 48. Not because pregnancy is likely, but because it is possible, and because a woman of 46 whose periods stopped may simply be having a very long gap rather than a final one. The younger you are when they stop, the less certain the ending.
Guidance varies a little between countries; some use twelve months regardless of age. If you are outside the UK, ask your own clinician which rule applies to you. The principle does not vary: the end is defined backwards, and you only know it after the fact.
HRT is not contraception.
This deserves its own line because the misunderstanding is so widespread and so consequential. HRT replaces hormones to treat symptoms. It does not reliably prevent ovulation. A woman on HRT in perimenopause who has stopped using contraception is not protected, and the bleeding pattern HRT produces will not tell her whether her own cycles have ended.
The combined pill is different, and can do both jobs for suitable women up to 50, managing symptoms and preventing pregnancy at the same time. That is a conversation worth having with your doctor if it applies to you. See hormonal vs non-hormonal contraception and our guide to HRT.
The obvious move is a blood test. Check FSH, confirm menopause, stop worrying.
It does not work, and the reason is the same reason perimenopause is hard to diagnose at all. Your hormones swing violently through the transition. FSH can be in the menopausal range one month and back to normal the next, and a raised FSH on a single day tells you about that day. Research following women through the transition has found oestradiol rising in a substantial proportion before their final period, not falling. Any test that can be normal on Tuesday and menopausal on Friday cannot be the basis for a decision you cannot undo.
This is why guidance points clinicians at symptoms rather than FSH in women over 45, and why there is no test that says you are finished. The only definition of menopause is retrospective: twelve months without a period, counted afterwards.
There is one exception worth knowing. Women using progestogen-only methods, where periods often stop or become erratic because of the method, can have an FSH checked from age 50, and if it is above 30 IU/L, may continue for one further year and then stop. That is a specific pathway for a specific problem, not a general permission to test.
More on the wider question in should you get your hormones tested.
Fertility falls sharply through the forties. By 45, natural conception is uncommon. By 50, it is rare. Rare is not never, and the women it happens to are not doing anything unusual: they are simply having sex without contraception, at an age when they had reasonably concluded they no longer needed it.
There is a second reason to stay careful. Pregnancy in the mid-forties carries higher risks for both mother and baby, including miscarriage, chromosomal conditions, gestational diabetes and high blood pressure. Nobody in this position wants to be making that decision by accident.
And a third, quieter reason: rates of sexually transmitted infections in women in their late forties and fifties have been climbing. Condoms have a second job, and menopause does not retire it.
Perimenopause is one of the few times a contraceptive choice can do two jobs at once, and it is worth choosing on purpose rather than by inertia.
The right answer depends on your bleeding, your symptoms, your migraine history, your blood pressure and your preferences. That is a ten-minute conversation with a nurse, and it is worth booking.
Take a test. A pregnancy test works perfectly well in perimenopause; it is FSH that misleads, not hCG. Missed periods, nausea, sore breasts and exhaustion look exactly like the transition, which is precisely why late pregnancies are so often noticed late.
Emergency contraception still applies in your forties. Nothing about perimenopause changes that.
You do not need to be frightened. You need a date.
Work out which rule applies to you, one year after your last period if you are over 50, two years if you are under, 55 at the outside, and mark it. Until then, use something. The point is not that pregnancy is likely. The point is that the decision to stop should be a decision, made on a rule, rather than a drift that happens because nobody ever told you when the finish line was.
Can you get pregnant in perimenopause?
Yes. Ovulation continues, unpredictably, until it stops for good. Irregular periods and hot flushes do not mean you are infertile.
When can I stop using contraception?
UK guidance: one year after your last period if you are over 50, two years if you are under 50, and everyone can stop at 55. Guidance differs slightly between countries, so confirm with your own clinician.
Does HRT prevent pregnancy?
No. HRT is not contraception and does not reliably stop ovulation. If you need protection, you need a contraceptive method alongside it.
Can a blood test tell me I am no longer fertile?
Not reliably. FSH swings through perimenopause and can look menopausal one month and normal the next, which is why guidance advises against relying on it in women over 45.
Can you get pregnant if your periods have stopped for six months?
Yes. A gap of several months is common in late perimenopause and can still be followed by ovulation and a period.
What is the best contraception in perimenopause?
Often the hormonal coil, because it prevents pregnancy, calms heavy bleeding and can form the progestogen half of HRT. The best method for you depends on your symptoms and medical history.
Sources: Faculty of Sexual and Reproductive Healthcare, Contraception for Women Aged Over 40 Years · NICE NG23, Menopause: diagnosis and management · Tepper PG et al., oestradiol and FSH trajectories through the menopausal transition (SWAN), J Clin Endocrinol Metab 2012;97(8):2872-80 · UK guidance; rules differ by country. Educational only, not medical advice.
Keep reading: Hormonal vs non-hormonal contraception · Perimenopause vs menopause: the difference · Heavy and erratic periods in perimenopause · Trying to conceive over 35 · Find your menopause stage (free) · Take the free Hormone Quiz