Irregular or Absent Periods: Causes, Tests and When to Seek Help
Key message: A cycle can vary, but repeated long gaps, newly irregular bleeding or absent periods need a…
Key message: A cycle can vary, but repeated long gaps, newly irregular bleeding or absent periods need a pregnancy check and focused assessment. The aim is to identify the cause and protect bone, metabolic, fertility and endometrial health.
Get urgent help: Seek urgent care for a positive pregnancy test with pain, bleeding, shoulder-tip pain or fainting; very heavy bleeding with weakness; sudden severe pelvic pain; severe headache or visual symptoms; or acute illness.
What counts as irregular or absent periods?
Cycles are irregular when timing varies widely, periods are very far apart or the pattern changes from your usual rhythm. Amenorrhoea means periods have stopped for a clinically significant interval.
The correct threshold depends on age, previous regularity, contraception, breastfeeding and pregnancy possibility; do not rely on one app prediction.
What is the first test?
A pregnancy test is the first step whenever pregnancy is possible, even with contraception or occasional bleeding.
Pain or bleeding with a positive test needs prompt assessment for ectopic pregnancy or miscarriage.
What common causes are considered?
- PCOS/PMOS and irregular ovulation.
- Weight loss, low energy intake, intensive exercise or major stress.
- Thyroid disease or raised prolactin.
- Premature ovarian insufficiency or perimenopause.
- Breastfeeding and the postpartum period.
- Hormonal contraception or medicines.
- Chronic illness or structural uterine/ovarian disease.
What history and examination matter?
- Cycle dates, pregnancy risk and contraception.
- Weight change, diet, exercise, stress and sleep.
- Hair growth, acne, scalp hair loss or skin changes.
- Hot flushes, vaginal dryness or reduced libido.
- Milky nipple discharge, headaches or visual symptoms.
- Pelvic pain, abnormal bleeding and fertility goals.
- Medication, thyroid, chronic disease and family history.
Which tests may be offered?
AMH is not a universal diagnostic test for absent periods and is not the primary test for premature ovarian insufficiency.
- Pregnancy test.
- TSH and prolactin.
- FSH and estradiol when ovarian insufficiency or menopause is suspected, with timing/repetition according to the clinical pathway.
- Androgen tests when PCOS or rapid virilisation is suspected.
- Glucose, lipids or other metabolic testing for PCOS risk.
- Pelvic ultrasound when structural or ovarian assessment is useful.
Why do long gaps matter?
Long-term low estrogen can affect bone and cardiovascular health, while repeated anovulation with ongoing estrogen exposure can leave the endometrium without regular progesterone protection.
The treatment therefore depends on whether the problem is low estrogen, PCOS-type anovulation, contraception, pregnancy or another cause.
How is treatment chosen?
- Treat the underlying thyroid, prolactin, nutritional or medical cause.
- Restore adequate nutrition and reduce excessive exercise when energy deficiency is present.
- Use cycle regulation or regular progestogen for endometrial protection in selected anovulatory patients.
- Offer hormone replacement for premature ovarian insufficiency when appropriate and not contraindicated.
- Use fertility-directed treatment only after a couple-based assessment when pregnancy is desired.
When is rapid referral needed?
- Rapid deepening of the voice, muscle change or severe new androgen symptoms.
- Headache with visual change or neurological symptoms.
- Possible premature ovarian insufficiency before age 40.
- Significant eating disorder, very low weight or medical instability.
- Pelvic mass, severe pain or persistent abnormal bleeding.
- Primary amenorrhoea or delayed puberty requiring specialist assessment.
Frequently asked questions
Can stress stop periods?
Yes, but pregnancy and medical causes still need consideration.
Does irregular bleeding always mean PCOS?
No. Many endocrine, reproductive, medical and medication causes are possible.
Should I take the pill just to make a bleed?
Cycle treatment should follow assessment of the cause, health risks and pregnancy plans.
Does no period mean no pregnancy risk?
No. Ovulation can occur before the next bleed.
Is AMH the test for absent periods?
No. It may answer selected ovarian-reserve questions but does not replace pregnancy, FSH, thyroid, prolactin and clinical assessment.
Your next step
Bring at least several months of cycle dates, pregnancy tests, medicines and changes in weight, exercise or symptoms. Long gaps should be reviewed even when pregnancy is not currently desired.
Medical and content review: Dr Mohamed Abdelghany, Obstetrics & Gynecology Specialist, MRCOG (UK), MSc Obstetrics & Gynecology – Kasr Al-Ainy, Cairo University.
Last reviewed: 23 August 2026.
This information is for general education and does not replace individual medical assessment. Severe, sudden or concerning symptoms should not wait for a routine appointment.
