When periods stop: amenorrhoea

When periods stop after you have previously had them, pregnancy is the first possibility to consider. Clinicians call this change secondary amenorrhoea. They will also look at your health history, medicines and other possible causes.

If pregnancy is possible

The NHS says most pregnancy tests can be used from the first day of a missed period. If you do not know when the next period is due, test at least 21 days after you last had unprotected sex. Follow the instructions for the particular test.

Call 999 now (UK) or 911 (US), or your local emergency number, if you have sudden severe tummy pain with marked dizziness or fainting.

Contact an urgent GP service or NHS 111 now (UK), or your doctor or urgent care service (US or elsewhere), if pregnancy is possible and you have one-sided lower tummy pain, vaginal bleeding or shoulder-tip pain, even without a positive pregnancy test. Do not wait to repeat a test if these symptoms occur.

If a result is negative but you still think pregnancy is possible, wait a few days and test again. Speak to your GP or doctor if the repeat test is negative and your period has not arrived. The hormones in contraceptive pills do not stop a pregnancy test working.

When to book an appointment

In the UK, the NHS advises a GP appointment if you have missed your period 3 times in a row. It also advises a check for a missed period with symptoms such as weight change, tiredness, facial hair growth or skin changes, and for periods that have become irregular.

US specialist guidance from ASRM uses more than 3 months without periods after previously regular cycles, or 6 months after irregular cycles, as thresholds for investigation. These are different ways of describing when assessment is needed. They are not instructions to wait when you have pregnancy concerns or other symptoms.

What might be affecting your cycle

Breastfeeding and some hormonal contraception can stop bleeding. Stress, sudden weight loss, higher body weight and intense exercise can also be associated with missed periods. Your clinician will look at these circumstances together; a period record cannot tell you which explanation applies.

Conditions considered include an underactive or overactive thyroid, raised prolactin, premature ovarian insufficiency and PCOS. You may now see PCOS called polyendocrine metabolic ovarian syndrome, or PMOS, on the NHS website. These conditions need different assessments and treatments, even though they can all affect bleeding.

Functional hypothalamic amenorrhoea describes what happens when the brain’s hormone signalling is affected in a setting that can involve energy imbalance or stress. It is considered only after other causes have been excluded. Assessment includes eating and exercise patterns, changes in weight, sleep, mood and any history of fractures.

What happens during the assessment

Your clinician may ask when periods first began, what the pattern was before they stopped and whether you have had recent treatment or surgery. Depending on your history and examination, blood tests can include pregnancy testing, thyroid function, prolactin and FSH. An ultrasound may help with the assessment; not everyone needs every test.

Bring the names of prescribed medicines and contraception, and describe what has changed, even if you are unsure why. If eating, training or stress is difficult to talk about, say that at the start. You could ask, “What are we checking first, and what happens if those tests do not explain it?”

Care after a cause is found

Treatment depends on what is causing your periods to stop. For functional hypothalamic amenorrhoea, care may involve improving nutrition, reducing exercise demands and psychological support. Bone health may also need assessment. The Endocrine Society advises against using the contraceptive pill solely to restore periods or improve bone density in this condition.

During recovery from functional hypothalamic amenorrhoea, bleeding may be irregular and pregnancy can still occur. If you want to avoid pregnancy, include contraception in the discussion with your clinician. If you are hoping to conceive, ask how that changes the care plan while nutrition, activity and hormone function are being addressed.

Book with a GP in the UK, or your doctor in the US or elsewhere, using the advice above. Ask when results will be reviewed and who to contact if symptoms change.