Irregular Periods: Causes, What They Signal, and How Tracking Helps
What Counts as Irregular
A cycle is irregular if: it varies by more than 7 days between months; it’s consistently shorter than 21 days or longer than 35 days; periods are missed for 3+ months (amenorrhea); or bleeding is unpredictably heavy or light. Occasional variation of 3–4 days is normal.
Common Causes of Irregular Cycles
PCOS (polycystic ovary syndrome): most common cause in reproductive age, due to excess androgens disrupting ovulation. Thyroid disorders: both hypo- and hyperthyroidism disrupt the HPG (hypothalamic-pituitary-gonadal) axis. High stress or low body weight: cortisol and energy restriction suppress GnRH. Perimenopause: begins 5–10 years before menopause in some women, causing increasing irregularity.
How Tracking Reveals the Pattern
Without tracking data, it’s difficult to tell a doctor what’s irregular. 6 months of logged cycle dates provides: average cycle length, standard deviation, longest and shortest cycles, and flow patterns. This data is what physicians use to distinguish benign variation from pathological irregularity. Cycle Tracker computes these statistics automatically.
When to See a Doctor
See a doctor if: cycles are absent for 3+ months, consistently shorter than 21 or longer than 35 days, sudden change in pattern (especially with other symptoms), heavy bleeding soaking through a pad/tampon every 1–2 hours, or pain interfering with daily life.
Frequently Asked Questions
Track your cycle
Open Cycle Tracker to log your period dates and identify irregularity patterns over time.
Open Cycle Tracker