What to look at when your cycle is irregular
How stress, sleep, and weight changes affect it
How many days is a normal cycle?
The common range is 24–38 days. But what matters more than the number is how similar it is month to month. Someone with a steady 30-day cycle counts as regular.
The American College of Obstetricians and Gynecologists (ACOG) considers a cycle regular when the variation is 7 days or less.
So if your shortest cycle was 27 days and your longest was 30, that is a 3-day spread. Under 7 days, so regular.
If your shortest was 23 days and your longest was 34, that is an 11-day spread, which counts as irregular.
LunaCat works out your regularity from 2 to 6 cycles within the last year.
What makes a cycle irregular
Most people see their period pattern change several times over their life. Skipping a period or going irregular for a while is common even when you are perfectly healthy.
Ongoing irregularity can point to a condition
Mistyped period dates can also make your cycle look irregular. You can correct past cycles in the calendar any time.
When to see a doctor
The occasional cycle outside the normal range is fine if it settles back. But talk to a healthcare professional if any of these apply.
LunaCat is not a diagnostic tool. Always take questions about your cycle to a doctor or qualified healthcare professional.
Puberty (often irregular for the first year or two)
Perimenopause
Miscarriage or abortion
Hormonal birth control (the pill, an IUD, emergency contraception)
Losing or gaining a lot of weight
Very heavy exercise
Stress or intense emotion
Travel (time zone changes, disrupted sleep)
Sleep problems (night shifts, insomnia)
Polycystic ovary syndrome (PCOS)
Thyroid problems
Unmanaged diabetes
Pelvic inflammatory disease
Uterine polyps or fibroids
Primary ovarian insufficiency (early menopause)
No period for 90 days or more and you are not pregnant
Cycles shorter than 24 days or longer than 38 days
A regular period that suddenly turns irregular
Irregular cycles along with trouble getting pregnant
Bleeding between periods
Severe pain during your period
A period lasting more than 8 days
Bleeding heavy enough to soak a pad every one to two hours
Sources
- Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles — npj Digital Medicine, 2019
- Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign — ACOG Committee Opinion
- Abnormal Uterine Bleeding — ACOG
- FIGO systems for normal and abnormal uterine bleeding: 2018 revisions — Int J Gynecol Obstet, 2018