Effects of Irregular Periods

An irregular cycle may be shorter, longer, skipped, or unpredictable. Changes in ovulation can make it harder to identify fertile days and can make pregnancy timing less predictable. When ovulation does not occur, the womb lining may build up and then shed unpredictably, causing spotting or a heavier bleed. Causes include stress, weight change, thyroid disorders, [Polycystic Ovary Syndrome](/conditions/polycystic-ovary-syndrome/), [Perimenopause](/conditions/perimenopause/), [Premature Ovarian Insufficiency](/conditions/premature-ovarian-insufficiency/), and [Anovulation](/conditions/anovulation/). Irregular periods are a symptom, not a diagnosis, so the same pattern can have different explanations.

Record the first day of each bleed, how long it lasts, flow changes, pain, medicines, and other symptoms. Note acne, increased facial hair, hot flushes, nipple discharge, or changes in weight because these details help guide assessment. Take a pregnancy test when relevant, even if bleeding is unusual. A clinician may review thyroid function, hormones, blood count, or pelvic health depending on your history. Treatment is chosen for the cause and your goals; options can include the [Combined Pill](/treatments/contraception-and-family-planning/combined-pill/) or [Metformin for PCOS](/treatments/medical-gynaecology/metformin-for-pcos/).

Arrange medical review for periods that remain unpredictable, repeated skipped bleeds, bleeding between periods, bleeding after sex, new severe pain, or symptoms of anaemia such as unusual tiredness or breathlessness. Seek urgent care for very heavy bleeding with dizziness or fainting, severe pelvic pain, or bleeding during pregnancy. A missed period with significant pain needs prompt assessment because pregnancy-related problems can present this way.

Ask which causes fit your pattern, whether ovulation is occurring, what tests are appropriate, how to protect the womb lining, and which treatment supports your pregnancy or contraception plans.