Amenorrhea: definition and meaning
Amenorrhea is the absence of menstrual periods. Primary amenorrhea means periods haven't started by age 15. Secondary amenorrhea means periods stop for three months or more in someone who had regular cycles, or six months if cycles were irregular. Pregnancy is the most common cause, but stress, weight change and hormone conditions are frequent too.
The two types
| Type | What it means | Common causes |
|---|---|---|
| Primary | No first period by 15 | Late puberty, genetic or anatomy differences, hormone problems |
| Secondary | Periods stop for 3+ months | Pregnancy, breastfeeding, stress, low weight, intense exercise, PCOS, thyroid problems, menopause |
Some causes are natural: pregnancy, breastfeeding and menopause all pause periods. Others happen when the brain dials down the hormones that run the cycle, as in hypothalamic amenorrhea. Conditions like PCOS and thyroid problems can also stop ovulation, and without ovulation a period often doesn't come.
Why it matters
Periods are a sign that your hormones are working as expected. Long stretches without them can mean low estrogen, which over time affects bone health, or an untreated condition worth catching early. Missing periods can also bring a lot of worry, and that stress can make things harder. Read the full guide: what is amenorrhea.
Take a pregnancy test first if you could be pregnant. Then see a doctor if you've missed three periods in a row, if you're 15 or older and haven't started, or if missed periods come with hair growth, headaches, vision changes or milky nipple discharge.
Frequently asked questions
How many missed periods count as amenorrhea?
Doctors usually use three missed periods in a row for regular cycles, or six months without a period for irregular ones.
Can stress cause amenorrhea?
Yes. Big stress, under-eating and heavy training can switch off the brain signals that trigger ovulation. This is called hypothalamic amenorrhea and is often reversible.
Sources
- Cleveland Clinic: Amenorrhea
- MedlinePlus: Absent menstrual periods, secondary
- NHS: Stopped or missed periods
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
What is amenorrhea?Amenorrhea means absent periods: no period by 15, or no period for 3 months or more. The types, common causes from stress to PCOS, and how it's treated.
What is secondary amenorrhea?Secondary amenorrhea means your periods stop for 3 months or more after you've had them before. Common causes, tests, and when to see a doctor.
Hypothalamic amenorrhea: definition and meaningHypothalamic amenorrhea: periods stop because the brain dials down cycle hormones, often from stress, under-eating or hard training. Causes and recovery.What is oligomenorrhea?Oligomenorrhea means infrequent periods, with cycles longer than 35 days or fewer than 9 periods a year. Common causes like PCOS, and when to see a doctor.
Why did my period stop?Why did my period stop? Pregnancy first, then stress, weight change, exercise, PCOS, thyroid, birth control or perimenopause. What to check and when.