Symptoms & care · 6 minute read
Irregular cycles: patterns, causes, and tracking
What “irregular” can mean, common reasons timing changes, and which details help at a medical visit.
Evidence-informed · Editorial review August 2026 · Links to trusted sources are available in the interactive app
Variation exists on a spectrum
A cycle can arrive a few days earlier or later without signaling disease. Repeatedly short, long, skipped, or unpredictable cycles are more useful to discuss with a clinician than one unusual month.
Many factors can affect timing
Pregnancy, stress, major weight change, intensive exercise, illness, thyroid conditions, PCOS, medications, breastfeeding, and perimenopause are among the possibilities. Tracking cannot determine which cause applies.
Bring a clear record
Log cycle start dates, bleeding duration and heaviness, pain, pregnancy tests, medicines, and major health or lifestyle changes. That record helps a clinician decide which questions, examination, or tests are appropriate.