Hypothalamic Amenorrhoea: When Stress Stops Periods

By Dr Victoire Kotur de Castelbajac, Medical Gynaecologist, GMC No. 7982441

The woman in front of me is usually well. She runs, she works hard, her blood results have been called normal, and someone has already told her to relax. In my London clinic, "my periods stopped when I moved here" is one of the commonest opening sentences I hear — and a move is a genuine stressor, not a coincidence to smile at. What nobody has told her is that "stress" is a diagnosis you are only allowed to make after the tests come back clear.

Functional hypothalamic amenorrhoea (also spelled amenorrhea) is the loss of periods caused by the brain reducing its pulsed hormone signal to the ovaries, usually under stress, low energy availability or heavy training. It is a diagnosis of exclusion: it is confirmed only once pregnancy, thyroid, prolactin and ovarian causes have been ruled out.

Below is the order a gynaecologist actually works in: what has to be ruled out, what is really being asked of your body, and what genuinely restarts a cycle.

Why "it's just stress" is not a diagnosis — it's a conclusion

Functional hypothalamic amenorrhoea (FHA) is a diagnosis of exclusion: it is what remains once other causes have been excluded, not an explanation offered instead of testing. The Endocrine Society's guideline (Gordon et al., 2017) is explicit — anatomic and organic causes are ruled out first, and only then does the label belong to you.

Periods that stop for three cycles or more, in someone whose cycles were previously regular, are called secondary amenorrhoea. That is a description, not a cause. Several quite different things hide behind it: pregnancy, still the most common answer and the reason a test comes first even when you are certain; thyroid disease, over- or underactive; a raised prolactin level, from medication or from a small benign pituitary tumour called a prolactinoma; premature ovarian insufficiency, where the ovaries are running out early; polycystic ovary syndrome; and, uncommonly but importantly, Cushing's syndrome. Each has a different fingerprint and a different test that finds it — the table further down sets them side by side, so you can see where your own story fits.

One published case shows how easily this goes wrong. A woman in her forties was referred for abnormal uterine bleeding with a working diagnosis of perimenopause. Her main complaint was hot flushes she had had for more than two years, and she also had stretch marks, newly diagnosed diabetes and high blood pressure. Everything about the picture sounded like a hormonal transition. It was Cushing's syndrome, caused by long-acting corticosteroid injections she had been having into several joints every two to three months for about five years (JCEM Case Reports, 2024). A plausible hormonal story is not a diagnosis.

By the time someone reaches me, "it's just stress" has usually been used as a reason not to investigate, which is precisely the wrong way round. Stress is a plausible explanation. It is not a substitute for a pregnancy test, a defined blood panel and a pelvic ultrasound as part of the work-up.

How stress actually stops a period

Your ovaries are not broken. The pulsed signal from the hypothalamus that drives them has been turned down.

GnRH, the hormone at the top of the chain, is not released steadily. It arrives in bursts, and the rhythm of those bursts is the message. A small population of neurons in the arcuate nucleus of the hypothalamus — called KNDy neurons, because they release kisspeptin, neurokinin B and dynorphin — generates that rhythm, and kisspeptin is the final common pathway into the GnRH cells. When metabolic and psychological stressors activate the HPA axis and raise CRH, the pulses slow and flatten. The pituitary has less to respond to, so it releases less LH and FSH, and the ovaries — perfectly capable ovaries — are never asked to grow a follicle.

Which is why the bloods look so unremarkable at a glance: low oestradiol alongside LH and FSH that sit low or low-normal. The medical term is hypogonadotropic hypogonadism. Out of context, "your FSH is normal" is technically true and clinically misleading: with a low oestradiol, a normal FSH is itself the abnormal finding.

The trigger is rarely one dramatic event. Training load, under-eating, broken sleep, a demanding job, a bereavement, a move to a new country — these stack. The cycle stops when the total becomes too much, not when any one item looks extreme.

"But I'm not underweight" — why weight is the wrong measure

FHA occurs at normal body weight, because the determinant is energy availability rather than body mass index. What matters is how much energy is left for your body to run everything else on once training has taken its share — not the number on the scale.

This is the correction I most often have to make, and I want to be plain about it: I do not need a number from you to work this out, and I will not be giving you one. Energy availability is a relationship, not a threshold you can look up and then argue with yourself about. Sports medicine describes low energy availability as a spectrum, from an adaptable state the body absorbs without visible cost to a problematic state with measurable consequences — the framework published as Relative Energy Deficiency in Sport (REDs) by the International Olympic Committee (Mountjoy et al., 2023). Absent periods sit at the problematic end.

Two consequences follow. Losing weight deliberately, sensibly, from a starting point nobody would have called high, can still stop a cycle — the body responds to the deficit, not to where you began. And stress and under-fuelling and training all draw on the same account. A woman training moderately through a brutal work year can end up in the same place as an athlete training far harder while eating well.

If your periods stopped when your training changed, the piece on training, under-fuelling and your cycle covers that side in more detail. What it cannot do is tell you whether something else is going on. Only the work-up does that.

The work-up: what should actually be checked

The diagnosis is made with a history, an examination, a defined set of blood tests, a pelvic ultrasound and — in some cases — a pituitary MRI and a bone density scan. Not with a conversation about your stress levels.

A pregnancy test comes first, always, however confident you are. Then the blood panel the Endocrine Society guideline sets out (Gordon et al., 2017), and the reason each test earns its place:

• TSH and free T4 — thyroid disease in either direction can stop periods, and it is straightforward to treat.
• Prolactin — a raised level points to medication effects or a prolactinoma, the thing no lifestyle programme can find.
• LH and FSH — these locate the problem. Low or low-normal levels put it above the ovary, in the hypothalamus and pituitary; a clearly raised FSH points instead to the ovary failing early.
• Oestradiol — tells us how much oestrogen your body is actually running on, which matters for bone.
• AMH — a marker of ovarian reserve, useful here for separating hypothalamic amenorrhoea from premature ovarian insufficiency.
• Testosterone and DHEA-S — added when there are signs of raised androgens, such as acne or unwanted hair growth.

A pelvic ultrasound looks at the ovaries and at the lining of the womb, which is usually thin when oestradiol has been low for months. A pituitary MRI is considered when prolactin is raised, or when there are headaches or changes in vision. French endocrinology practice goes further and images the pituitary whenever gonadotrophins come back low — that is the Société Française d'Endocrinologie position rather than Endocrine Society guidance, and it is one reason my threshold for scanning is lower than you may be used to here. A baseline DXA bone density scan is advised after six or more months without periods, and earlier where there is particular concern about the skeleton — a moderate-strength recommendation rather than an absolute one, but one I follow.

Three missed periods is also where UK guidance sits — NHS advice is to see a doctor when you have missed three periods in a row. So the disagreement between the two countries I work in is not about the threshold. It is about what happens next. In French practice, presenting at three months triggers the full hormonal panel, and the pituitary is imaged if gonadotrophins are low. Here, the same presentation more often leads to a repeat pregnancy test, a wait-and-see interval, or an offer of the pill before anyone has measured a prolactin. That gap is what I close, not the three months. You do not have to be reassured twice before you are investigated.

What it costs to leave it — bone, heart and fertility

Long-running low oestrogen affects more than your periods: bone density falls, and vascular function can be measurably impaired.

Bone is the clearest stake. Oestrogen restrains bone breakdown, so months without it mean bone mineral density drifts down and fracture risk rises — which is why the six-month DXA threshold exists, and why I would rather have a baseline than guess. There is more on how low oestrogen affects bone density in the piece on bone health; the biology is the same at thirty as at fifty.

The vascular finding is newer and more easily overstated, so let me be careful. In a US research programme (Shufelt et al., 2026), 35% of women with FHA had a reactive hyperaemic index in the range that indicates endothelial dysfunction — the blood vessels' inner lining responding less well than expected. That is a measured difference in a small group of women, not a prediction that you will have a heart attack — but it is a reason to treat prolonged absent periods as a whole-body matter.

Fertility is where most of the fear sits, and it is the least frightening part. FHA suppresses ovulation rather than depleting the ovarian reserve, and it is not early menopause. In most women the axis recovers and so does ovulation. If conception is on your mind now rather than later, the first steps if you're trying to conceive are worth reading alongside this — but the honest order is work-up first, recovery second, fertility treatment only if still needed.

Will my period come back — and when?

For most women FHA is reversible, but there is no reliable timeline. Recovery is measured in months rather than weeks, and it depends on how long cycles have been absent and how fully the underlying energy and stress load is corrected.

The "three to six months" you have read everywhere is expert experience and small case series, not trial evidence. I say that out loud because it changes how you should hold it: an order of magnitude, not a promise, and certainly not a schedule you have failed to meet. Recovery tends to take longer when cycles have been absent for years rather than months, when the energy deficit is still running, and when the stress that started it has not changed.

Then there are "recovery signs", which deserve an honest answer. Changes in cervical mucus, breast tenderness or premenstrual symptoms can appear before any bleeding, and they are genuinely encouraging. They are not proof. Equally, one bleed does not mean the axis is stable — it means one cycle happened.

Two practical points fall out of that. A cycle can restart without much warning, so if pregnancy would be unwelcome you still need contraception during recovery — I would not assume that no bleeding means no ovulation. And progress can be measured rather than guessed: repeat oestradiol, LH and FSH, an ultrasound to look at the endometrium and for developing follicles, and a repeat DXA where bone was a concern.

I cannot tell a woman exactly when her period will return. I can tell her what makes it sooner rather than later, and I can measure whether the axis is waking up. In my experience that is more reassuring than a number would have been.

So I set a review date instead of a deadline. Three months is usually about right: long enough for a real change in fuelling and training to show up in the bloods, short enough that nothing drifts. A review date, not a due date. If the numbers have moved in the right direction, that is progress you can see, even in a month when nothing bleeds.

Eating disorders, and when this needs more than a gynaecologist

If food, weight or exercise feels difficult to control, that needs support in its own right — and getting it does not delay your gynaecological care. The two run in parallel.

Disordered eating and FHA overlap, and either can exist without the other. Plenty of women with absent periods have no eating disorder. Plenty of women with a difficult relationship with food have entirely regular cycles. What I will not do is guess, or make you prove anything before you are investigated.

My threshold for involving other clinicians is deliberately low. If there is any suggestion that eating, exercise or body image is driving this, I would rather bring in a dietitian and a psychologist early than leave someone managing it alone. You will not be weighed and lectured in my clinic.

If this is true for you and you want support that has nothing to do with a gynaecologist, Beat runs the UK eating disorder helplines, open 3pm to 8pm, Monday to Friday: England 0808 801 0677, Scotland 0808 801 0432, Wales 0808 801 0433, Northern Ireland 0808 801 0434. You do not need a diagnosis to call.

What actually helps — and what only looks like it helps

The strongest recommendation is to correct the underlying energy imbalance. Hormone replacement can support bone in the meantime, but it does not restart the axis.

Correcting energy availability is the guideline's strong recommendation, on moderate-quality evidence: eating more, training less, and doing it with someone qualified beside you rather than alone with an app. In practice that usually means a dietitian who works with this specific problem, and behaviour change that is harder than it sounds. A whole-person assessment of energy, stress and cycle recovery is how I structure that side of it.

Psychological support, including CBT, is suggested alongside the nutritional work — a weak recommendation on low-quality evidence, and I will not dress it up. The trial people quote (Berga et al., 2003) found ovarian activity in 87.5% of women who had CBT versus 25% of those observed, in a randomised trial of sixteen women. Sixteen. That is a signal worth acting on, not an established treatment effect, and anyone quoting the percentages without the sample size is selling something.

The combined pill is suggested against when the only purpose is to regain periods or protect bone. It produces a withdrawal bleed, which looks like recovery and can mask whether your own cycle has come back, and bone loss can persist despite it — a 2026 review found no significant bone-density benefit from the combined pill at any site (Efthymiadis et al., 2026). Taking it because you want contraception is a completely different and legitimate reason — a separate conversation, worth having explicitly.

Oestrogen replacement, which is prescription-only and always individualised, is positioned by the guideline as a short-term option after nutritional and psychological approaches have not restored cycles, on very-low-quality evidence. Two 2026 findings have changed how I discuss it. In a randomised trial of twenty-nine women with FHA (Shufelt et al., 2026), twelve weeks of transdermal oestradiol raised serum oestradiol roughly threefold compared with placebo, yet produced no significant improvement in vascular or psychological outcomes. The review cited above found the opposite pattern for bone: transdermal HRT improved bone density at the lumbar spine and femoral neck, while oral HRT showed no significant benefit at any site. So the route matters, and the splint metaphor holds. A patch can support the bone while the axis recovers. It is not what makes the axis recover.

No supplement appears in this section, because none has evidence in this condition.

When to be seen, and what happens in clinic

Three missed cycles with a negative pregnancy test is enough reason to be assessed. That is UK guidance as well as French practice, and it is the threshold I use.

Some things should not wait at all: a headache or any change in your vision, milk-like discharge from the nipples, hot flushes and night sweats, rapidly increasing acne or unwanted hair growth, or an eating disorder that feels out of control right now.

A first appointment is fairly ordinary in shape. We go through the history properly, including the timeline — when the training changed, when the job started, when you moved, when the last normal period was. There is an examination. Bloods are arranged, and a pelvic ultrasound often done on the day where indicated. If you have crossed the six-month mark, we discuss a bone density scan — what it would show, and how one is arranged. You leave with a written plan rather than a vague instruction to reduce your stress.

Bring your previous blood results if you have them. Most women in this position have several sets they were told were normal, and read together, with the dates, they often tell a clearer story than any single panel.

If your periods have stopped and you are not pregnant, a cycle assessment can establish why. Book a consultation with Dr Victoire Kotur de Castelbajac.

FAQ

Is hypothalamic amenorrhoea reversible?

In most women it is reversible, though the timeline varies and cannot be predicted precisely. The condition reflects a suppressed signal from the hypothalamus rather than damage to the ovaries, so cycles usually return once energy availability and stress load are corrected. It suppresses ovulation rather than depleting the ovarian reserve, and it is not early menopause.

How long does it take to get your period back?

There is no reliable figure. Recovery is measured in months rather than weeks, and the much-repeated "three to six months" comes from clinical experience and small case series, not from trials. It tends to take longer when periods have been absent for years, when an energy deficit continues, or when the original stress has not changed.

Can you have hypothalamic amenorrhoea at a normal weight?

Yes, and this is the most important thing to understand about it. The determinant is energy availability — how much energy remains for your body after training and daily demands — not body mass index. Functional hypothalamic amenorrhea is regularly diagnosed in women of entirely normal weight, including after deliberate weight loss from a higher starting point.

Can you get pregnant with hypothalamic amenorrhoea?

A cycle can restart before you see any bleeding, so pregnancy is possible before your first period arrives, and contraception is still needed during recovery if pregnancy would be unwelcome. Fertility usually recovers as the axis does. If you are actively trying to conceive, the work-up should come first, because the cause changes the plan.

Is hypothalamic amenorrhoea the same as PCOS?

No — in some respects they are opposites. In hypothalamic amenorrhoea, oestradiol is low with low or low-normal LH and FSH. In polycystic ovary syndrome, cycles are typically irregular rather than absent, and signs of raised androgens are common. They can be confused on an ultrasound alone; see how PCOS differs, and how it's diagnosed.

Does the pill bring your periods back?

It produces a monthly withdrawal bleed, which is not the same as your own cycle returning, and the guideline suggests against using it for that purpose alone or to protect bone — bone loss can continue despite it. Worse, the bleed can hide whether your axis has recovered. As contraception it remains a reasonable choice.

Your ovaries are almost certainly fine. The signal that drives them has been turned down, and the first job is to prove that nothing else is doing it — not because that is likely, but because it is the only way the word "stress" earns its place on your notes. Everything useful follows from that: what to correct, what to measure, what to leave alone. If your periods have stopped and you are not pregnant, a cycle assessment can establish why, and you are welcome to book a consultation with Dr Victoire Kotur de Castelbajac.

References

• Gordon CM et al. Functional hypothalamic amenorrhea: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2017;102(5):1413–1439.
• Shufelt CL et al. J Clin Endocrinol Metab 2026;111(2):e552–e559.
• Efthymiadis et al. J Clin Endocrinol Metab 2026;111(5):e1446–e1456.
• Berga SL et al. Fertil Steril 2003;80(4):976–981.
• Mountjoy M et al. 2023 IOC consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med 2023.
• Iatrogenic Cushing syndrome mistaken for perimenopause. JCEM Case Reports 2024;2(11):luae183.

Reviewed by Dr Victoire Kotur de Castelbajac, Medical Gynaecologist, GMC No. 7982441. Review date to be confirmed at sign-off.

This article is general information about a medical condition and does not replace advice about your own care. If your periods have stopped, see a doctor who can examine you and arrange the right tests. If there is any chance you are pregnant, take a test first.