What causes irregular periods?

A period may arrive early, late, become lighter or heavier, or be missed when ovulation changes. Anovulation means an egg is not released during a cycle and can lead to unpredictable bleeding. Polycystic Ovary Syndrome is one condition associated with irregular ovulation; raised prolactin, known as Hyperprolactinaemia, can also disturb the hormone signals that regulate periods.

Major stress, under-fuelling, intensive exercise, illness and substantial weight change can affect those signals. Perimenopause commonly makes cycles less predictable. Premature Ovarian Insufficiency can cause irregular or absent periods and needs assessment, especially when symptoms begin earlier than expected. Pregnancy is another cause of a missed period.

Track the first day of bleeding, how long it lasts, flow changes, pain, spotting and any missed cycles. Record contraception, medicines, exercise, eating patterns, stress, acne, increased facial hair, headaches or nipple discharge. If pregnancy is possible, take a pregnancy test and share the result with your clinician.

A clinician may ask about your cycle history and check for causes of altered ovulation or hormone signalling. Treatment depends on the cause and your goals. For some people with PCOS, Metformin for PCOS may be discussed alongside lifestyle and cycle-management options.

Arrange a review for a persistent change in your usual pattern, repeated missed periods, bleeding after sex or bleeding that is unusually heavy or prolonged. Seek urgent help for severe pelvic pain, fainting, pregnancy with pain or bleeding, or bleeding that makes you feel weak or unwell.

Ask whether your pattern suggests irregular ovulation, which tests are appropriate, and how pregnancy, contraception or medicines affect the interpretation. Discuss what bleeding changes should prompt urgent help and how to protect fertility or manage symptoms.