Premature ovarian insufficiency

Premature ovarian insufficiency - Understanding menopause before 40 with care and clarity

Clinical review September 2026

Hearing that ovarian function may be changing before 40 can be disorientating, especially if it arrives in the middle of conversations about periods, fertility or future plans. Premature ovarian insufficiency, often shortened to POI, means the ovaries are not functioning regularly before age 40. It is not the same as a simple switch being turned off: intermittent ovarian activity and occasional ovulation can still occur.

What the diagnosis means and what it does not

POI may cause absent or infrequent periods, hot flushes, sleep disturbance, vaginal dryness or fertility difficulty, but presentation varies. The diagnosis is usually based on symptoms or menstrual disturbance lasting at least four months and raised FSH on two samples several weeks apart; clinicians also exclude pregnancy and consider other causes. This is a diagnosis that deserves time, explanation and support, not a rushed corridor conversation.

Often no single cause is found. Possible contributors include chromosomal or genetic conditions, autoimmune disease, surgery, chemotherapy or radiotherapy, infection in rare circumstances, and unexplained variation. Depending on age and history, investigations may include chromosome analysis, fragile-X premutation testing and screening for associated autoimmune conditions.

Why replacement hormones are about health as well as symptoms

Oestrogen normally supports bones, cardiovascular tissues, the vagina and brain, as well as controlling symptoms. In POI, hormone replacement therapy or a combined hormonal contraceptive is generally recommended unless contraindicated, commonly until around the usual age of natural menopause. This is different from deciding whether to use HRT after the usual age of menopause: the starting risk and benefit context is different.

The exact regimen is individual. People with a uterus need progestogen with systemic oestrogen to protect the endometrium. Bone health, blood pressure, lipids and emotional wellbeing should be reviewed, alongside the practicalities of taking treatment in a way that works.

Fertility deserves honest hope

Spontaneous ovulation and pregnancy can happen in POI, so contraception is needed if pregnancy is not wanted. If pregnancy is wanted, referral to fertility specialists offers a space to discuss the possibilities, which may include donor eggs, embryos or adoption depending on circumstances and values. There is currently no reliable treatment that restores ovarian function for everyone; honesty here is kinder than false certainty.

Grief, anger and relief can all co-exist. Psychological support is part of good care, not an optional decorative extra. A detailed future page could cover diagnosing POI, fertility options, hormones and bone health.

Seek advice promptly

Contact a clinician about missed periods with menopausal symptoms under 40, or sooner with severe headaches, visual symptoms or other concerning features. If cancer treatment or surgery may affect ovarian function, fertility and menopause support should be discussed before and after treatment.

Important safety note

This page is for general education and cannot replace individual medical advice. Seek urgent help for severe symptoms, possible pregnancy with pain or bleeding, collapse, confusion, seizure, or any situation in which you feel acutely unwell. A clinician who knows your history can help tailor investigation and treatment.