Life stages
When do periods become regular?
Periods often take a few years to settle, and the NHS says most people have regular periods by 16 to 18. Periods usually begin around age 12, though some start earlier or later. Irregular periods are more likely in the first years and again when menopause is near.
When do periods usually start?
Around age 12, although some people start earlier or later. A delay in starting isn’t usually a cause for concern, according to the NHS.
Why are the first periods irregular?
Hormones are still settling into a pattern. The NHS says irregular periods are more likely when they first start during puberty. ACOG notes that periods may not occur regularly when a girl first starts having them, around age 9 to 14.
What can help in the early years?
Keep a note of period dates. A simple tracker or diary shows the pattern as it forms and is useful if you later see a doctor. It also helps with surprises, like a period arriving earlier than you expected.
When should I see a doctor?
See a doctor if:
- Periods haven’t started by 15.
- You’ve missed 3 periods in a row.
- Your periods are very heavy, painful or last more than 7 days.
- You bleed between periods.
Frequently asked questions
Is a 40-day gap normal in the first year?
Irregular periods are more likely in the first years, according to the NHS. A gap of more than 35 days counts as irregular, so mention it to a doctor if it worries you.
What age is too late for a first period?
The NHS suggests seeing a doctor if periods haven’t started by 15.
Can I use an app?
Yes. Seventh is a free tracker for iPhone and iPad that shows predictions as a range, which suits early cycles.
Sources
Seventh is a free period and cycle tracker for iPhone and iPad, by doogud. This article is general information, not medical advice. If something feels wrong, see a doctor.
