Menarche and irregular periods: what to know

After the first period, the brain and ovaries are still coordinating the signals that release an egg and build the womb lining. Some cycles may not release an egg, a pattern called anovulation, which can make bleeding arrive early, late or unpredictably. Stress, major changes in exercise or weight, thyroid problems, medicines and pregnancy can also alter bleeding.

Polycystic ovary syndrome may present with irregular periods alongside acne or increased facial hair, but irregular periods alone do not establish that diagnosis. Less commonly, reduced ovarian function can cause periods to become infrequent. The pattern, age, symptoms and examination all guide interpretation.

Use a calendar or app to record the first day of bleeding, how long it lasts, flow, pain and any spotting. Note acne, hair growth, headaches, dizziness, weight change and medicines. If pregnancy is possible, take an appropriate test. Eat regularly, avoid extreme exercise changes and do not start hormonal treatment without advice. A clinician may discuss observation, the combined pill or treatment aimed at an underlying condition such as PCOS.

Arrange an appointment if periods remain very irregular, stop for a prolonged interval, become much heavier, or cause pain, fatigue or missed activities. Seek urgent help for soaking through protection repeatedly, fainting, severe one-sided pain, or possible pregnancy with pain or bleeding. New symptoms of excess androgen or signs of illness also merit review.

Ask what cycle pattern is expected at your stage, whether pregnancy or another condition should be excluded, and whether blood tests or imaging would help. Discuss how any proposed pill or metformin treatment would affect bleeding, symptoms and contraception.