Amenorrhea: why periods stop and when to seek medical advice

One late period, then two. By the third month without a period, the question becomes difficult to put off: is something going on?

Amenorrhea is the medical term for the absence of periods in someone of reproductive age. It is not an illness in itself, but a signal. In three situations, it is perfectly normal: pregnancy, breastfeeding, and menopause. In all other cases, it indicates that something has become disrupted in the hormonal chain that controls the menstrual cycle. Prolonged stress, weight loss, overly intense training, or a hormonal disorder: the causes are numerous, often identifiable, and most of the time reversible.

Here’s how to recognize amenorrhea, what causes it, how it affects fertility and bones, and when to seek medical advice.

What is amenorrhea?

A simple definition, two distinct forms

The French National Health Insurance defines it as the absence of periods in a woman of menstruating age. This wording covers two very different situations, which have neither the same causes nor the same treatment.

The MSD Manual provides a useful distinction for secondary amenorrhea: the threshold of 3 months applies to women whose cycles were regular, and rises to 6 months or more when periods were already irregular. In other words, if you have always had an irregular menstrual cycle, a four-month gap does not have the same significance as it does for a woman whose periods are as regular as clockwork.

Not to be confused with a simple late period

A period occurs on average every 28 days, and this regularity indicates that the uterus, ovaries, pituitary gland, and hypothalamus are functioning in concert. A few days' variation is nothing abnormal, and neither is a week.

Two terms often come up and deserve to be distinguished:

• A late period is counted in days or weeks. It warrants a pregnancy test, not a hormonal assessment.
• Spaniomenorrhea refers to very widely spaced cycles. The French Society of Endocrinology considers it to have a clinical significance similar to that of amenorrhea: periods that occur only two or three times a year should be investigated as an absence of periods.

Finally, bleeding is not necessarily a period. Spotting or bleeding outside your period can create the illusion that the cycle is continuing even though ovulation has stopped.

The three perfectly normal situations

Amenorrhea indicates a dysfunction in the body, except in three situations where, on the contrary, it shows that everything is working as expected.

Pregnancy: the first thing to rule out

It is the most common cause of missed periods, and it is also the first thing to check systematically before considering anything else. This includes when contraception is being used, when sex seemed risk-free, or when you are absolutely convinced you are not pregnant.

A urine test is sufficient in most cases. During a consultation, a doctor may prescribe a blood beta-hCG test, which is earlier and more reliable. And no, amenorrhea is not always related to pregnancy: it is simply the first possibility to rule out because it is the most likely and easiest to check. It is also worth noting that it is still possible to get pregnant during your period, which puts the idea of a risk-free period into perspective.

Breastfeeding and the return of periods after childbirth

After giving birth, periods do not return immediately. During breastfeeding, prolactin blocks ovulation, and amenorrhea may last for several months. This is physiological, but it is not a reliable form of contraception.

The return of periods after childbirth then occurs at a date no one can predict, often with heavier bleeding than usual.

Menopause and the period leading up to it

Menopause is confirmed after one year without periods. It is preceded by a transition phase, perimenopause, which begins on average around age 47 and is marked by irregular cycles, more pronounced premenstrual syndrome with breast tenderness and mood swings, hot flashes, and night sweats.

During this period, entire months may pass without a period, and then a cycle returns. This is not amenorrhea requiring investigation, but an ovary gradually shutting down. However, be careful not to confuse it with early menopause: the same signs before age 40 warrant an assessment.

Causes of secondary amenorrhea

Once pregnancy has been ruled out, the investigation begins. The causes fall into broad categories, and the patient history often points the way well before blood tests are performed.

Stress, weight loss, and intensive exercise

This is the most common trio, and all three involve the same mechanism: the hypothalamus pauses the menstrual cycle because the body determines that the timing is unfavorable. This is known as functional hypothalamic amenorrhea.

• Significant stress or trauma. The French National Health Insurance notes that improving psychological well-being allows menstruation to return. Our article on how stress affects periods explains this process in detail.
• Dietary restriction and weight loss, with anorexia nervosa being the most severe form.
• Intense athletic training, when body fat becomes insufficient. Endurance sports, aesthetic sports, and weight-class sports are the most affected.

The Endocrine Society's guideline on this form of amenorrhea specifies two practical benchmarks. An assessment is warranted when the interval between cycles persistently exceeds 45 days, or when periods are absent for 3 months or more. It is also a diagnosis of exclusion: it is only made after other possible causes have been ruled out.

For athletes, the issue goes far beyond menstruation. It involves energy availability, recovery, and bone health, as discussed in menstruation and athletic performance.

Polycystic ovary syndrome

Polycystic ovary syndrome, or PCOS, affects 5 to 10% of women of childbearing age. It typically causes very long cycles, lasting more than 35 to 40 days, which can even progress to a complete absence of periods.

It is often accompanied by signs of hyperandrogenism: excessive hair growth, oily skin, and persistent hormonal acne in adulthood. It is the combination of these signs and longer intervals between cycles that points toward this diagnosis.

Excess prolactin and certain medications

Prolactin is the hormone responsible for lactation. When its level rises outside pregnancy and breastfeeding, it blocks ovulation exactly as it does after childbirth.

• A prolactin-secreting adenoma, a benign tumor of the pituitary gland, is treated with medication (bromocriptine) or, more rarely, surgery.
• Medications alone can be enough to raise prolactin levels: antidepressants, antipsychotics, and corticosteroids.

The warning sign is galactorrhea, meaning a discharge of milk unrelated to a recent childbirth.

Ovarian insufficiency, or early menopause

This means that the ovaries stop functioning before the age of 40. Possible causes include removal of the ovaries, pelvic radiotherapy, chemotherapy, autoimmune diseases such as Hashimoto's thyroiditis or autoimmune diabetes, and certain genetic abnormalities, including fragile X syndrome.

The diagnosis completely changes management, because it is no longer a matter of waiting for a spontaneous return but of arranging follow-up, particularly for bone and cardiovascular health.

Hormonal contraception and stopping the pill

Two opposite situations can look very similar from the outside.

While using contraception, the absence of periods is often expected. The MSD Manual states that contraceptives containing only a progestin, whether pills, injections, implants, or intrauterine devices, frequently cause irregular periods or amenorrhea, and that a combined pill taken continuously has the same effect. This is not a dysfunction, and we explain in detail what happens to your periods while taking the pill in a dedicated article.

After stopping the pill, several weeks without periods are normal while the hormonal axis resumes control. However, Assurance Maladie sets a clear limit: after 3 months, the situation should be investigated. Beyond this point, it is no longer just a consequence of stopping the pill; something else needs to be looked for. If you have questions about contraception, our guide to choosing the right pill for you reviews the options.

Uterine causes, which are less common

The hormonal axis may function perfectly and periods may still not appear, simply because the blood cannot flow out or the endometrium can no longer rebuild itself.

• Uterine synechiae, meaning the uterine walls have become stuck together after an abortion, curettage, or uterine revision.
• Cervical scar stenosis, an abnormal closure occurring after electrocautery or conization.

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This overview provides guidance but is not a diagnosis. Several causes may overlap, and the purpose of the assessment is precisely to distinguish between them. Other everyday factors can also affect cycle regularity; we have brought them together in our article on factors that disrupt your period, and exposure to endocrine disruptors is also something to monitor.

Causes of primary amenorrhea

In adolescents, the medical assessment starts with a simple observation: have the secondary sexual characteristics developed or not? The answer divides the possibilities into two categories.

When puberty has not begun

Pubertal development follows a fairly regular timeline: the areola enlarges around age 11, the breasts develop and pubic hair appears around age 12, and the first period occurs around age 13. Our article on puberty in girls explains these stages in detail.

When none of these secondary sexual characteristics is visible by age 16, the possible causes include:

• Constitutional delay of puberty, by far the most common cause, which resolves on its own.
• A chromosomal abnormality, particularly Turner syndrome.
• Early anorexia nervosa or intense athletic training.
• An endocrine disorder, particularly hypothyroidism.
• Ovarian damage following treatment, or dysfunction of the pituitary gland or hypothalamus.

When puberty has progressed normally

If secondary sexual characteristics are present, with developed breasts and pubic hair, the hormonal axis is functioning. The obstruction is therefore anatomical and affects the route the blood must take to leave the body.

• An imperforate hymen, which prevents drainage. It often causes cycle-related pelvic pain, with no external bleeding.
• A vaginal malformation.
• Absence of a uterus, known as Mayer-Rokitansky-Küster-Hauser syndrome. The MSD Manual estimates this agenesis at around one woman in 5,000.

The doctor relies on a clinical examination and a hand X-ray, which determines bone age and shows whether the body is delayed compared with chronological age. Treatments depend on the cause: hormone therapy, surgery in the event of an obstruction, or treatment of the underlying condition. To prepare calmly for the arrival of your period, our article on your first period answers the most common questions.

Symptoms associated with absent periods

Amenorrhea is rarely isolated. The symptoms that accompany it are often more informative than the absence of periods itself because they point to the hormone involved.

Signs suggesting a hormonal cause

• Galactorrhea, the discharge of milk unrelated to childbirth, points to excess prolactin.
• Hirsutism, with hair on the upper lip, chin, or between the breasts, and more broadly virilization, indicates excessive androgen production by the ovaries or adrenal glands.
• Headaches associated with visual field abnormalities suggest a pituitary tumor. This is the sign that warrants prompt medical attention.

Signs of estrogen deficiency

When amenorrhea is accompanied by a sharp drop in estrogen levels, the body reacts as it would during menopause: hot flashes and vaginal dryness. Fatigue, unusual sensitivity to cold, reduced libido, and sleep disturbances often complete the picture.

These signs are not merely uncomfortable. They indicate the risk to bone health described below, and they are why amenorrhea should not be left untreated simply because it does not hurt.

How is amenorrhea diagnosed?

The consultation and clinical examination

The consultation begins with a complete medical history, followed by a general examination that includes measuring weight and height and calculating BMI. The doctor looks for excessive hair growth, acne, and seborrhea. In cases of primary amenorrhea, they assess pubertal development precisely.

A gynecological examination, possibly accompanied by a smear test, may be offered with your consent and is not performed on virginal girls. The position of the uterus may sometimes be noted on this occasion, without any effect on the cycle: we have dedicated an article to the retroverted uterus to clear up this common misconception.

Hormone tests and imaging

The assessment is built in stages. The healthcare professional does not prescribe everything at once: each result guides the next.

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The French Society of Endocrinology emphasizes a point that is often overlooked: hypothalamic-pituitary MRI is recommended for all cases of hypothalamic amenorrhea. Amenorrhea attributed too quickly to stress therefore warrants this examination, if only to rule out a lesion.

Absence of periods, fertility, and pregnancy

Amenorrhea is not permanent infertility

Most often, no periods means no ovulation, and therefore no possibility of pregnancy as long as the situation continues. This is true, and understandably it is what causes the most concern.

But in most cases, it is also temporary. Amenorrhea linked to stress, weight loss, or exercise is reversible: Assurance Maladie explicitly notes that improving psychological well-being allows menstruation to return. Regaining weight, reducing training load, treating excess prolactin or hypothyroidism is very often enough to restart the cycle. Only certain causes, primarily premature ovarian insufficiency, have lasting effects on fertility and warrant specialist support.

You can ovulate before your periods return

This is the point everyone forgets, and it has very real consequences. Ovulation occurs about two weeks before menstruation; it does not follow it. A woman whose cycle resumes therefore ovulates before having any confirmation from bleeding.

In other words, amenorrhea can never be considered contraception, and the first cycle to return can result in a pregnancy before menstruation ever reappears. This is particularly true postpartum, when breastfeeding delays the return of menstruation without preventing it. Changes in cervical mucus are also one of the few signals that can help identify ovulation when there is no menstrual reference point, and the luteal phase that follows determines when menstruation will reappear.

The risks of established amenorrhea

Loss of bone density, the best-documented risk

This is the real reason why amenorrhea should not be allowed to continue indefinitely, and it is rarely explained during consultations. Estrogens protect the bones. When their levels collapse for months, bone mineral density decreases, with a risk of osteopenia followed by osteoporosis, and therefore fractures.

The Endocrine Society guideline gives a clear figure that is easy to remember: a bone mineral density scan using dual-energy X-ray absorptiometry (DXA) is suggested for every adolescent or woman with 6 months or more of amenorrhea, and earlier in cases of severe undernutrition or known bone fragility. Bone mass is built primarily before age 25, so prolonged amenorrhea during adolescence or young adulthood can have consequences much later.

Other effects

The MSD Manual also lists cardiovascular disorders among the long-term effects of estrogen deficiency. And when amenorrhea is instead caused by an excess of estrogen not balanced by progesterone, as in some cases of anovulation, the risk shifts in the other direction: prolonged bleeding, hyperplasia, and endometrial cancer.

Two opposing mechanisms, the same conclusion: a cycle that has stopped is never neutral, and the identified cause determines the follow-up. Regarding abnormal bleeding, our articles on blood clots during periods and periods and anemia complete the picture.

What to do when your periods do not return

What falls under the doctor's responsibility

Health Insurance sets out a rule that should appear in bold in every article on the subject: “The cause of amenorrhea must be diagnosed before any prescription is made.” It adds that taking a combined estrogen-progestin pill to regulate periods only causes artificial periods.

In practice, this means that a treatment that causes bleeding to return without identifying the cause does not treat anything. It simply makes the problem invisible. Care depends entirely on the diagnosis: treating hypothyroidism, lowering prolactin levels, supporting weight restoration, adjusting training load, operating to remove an obstruction, or starting hormone treatment in cases of ovarian insufficiency.

What you can do yourself

• Take a pregnancy test before anything else, even if it seems unnecessary.
• Note the date of your last period and how your cycles became more spaced out before stopping. This is the most useful information you can bring to your appointment.
• Review the past six months: weight loss, dietary changes, increased training volume, a period of intense stress, a new medication, or stopping contraception.
• Check your nutritional intake if you have reduced your portions. Our article on what to eat during your period provides guidance on iron and a balanced diet.
• Do not take anything on your own initiative to bring on your period. Herbs and remedies of this kind do not address the cause and can obscure the assessment.

The return of periods is often unpredictable

Three situations in which the date remains a surprise

When the underlying cause is treated or balance is restored, periods return. Without warning, and rarely when expected.

• After stopping the pill, the first spontaneous cycle arrives at a time that nothing can predict.
• After giving birth, the return of periods occurs at a variable time depending on breastfeeding, often with heavier flow than before pregnancy.
• After hypothalamic amenorrhea, regaining weight or reducing training can restart the cycle without warning.

In all three cases, the same scenario repeats: several weeks of checking, carrying protection just in case, or being caught off guard. Some people therefore choose to wear washable protection continuously, which settles the matter without having to think about it.

Protection you can wear without thinking about it

Period panties are worn like ordinary underwear. They are invisible, imperceptible, and absorbent if your period arrives. This is their only real benefit here, and it is purely practical: no longer having to anticipate a date you do not know.

The choice mainly depends on what you expect from your period: maximum discretion with the thong, absorbency with a medium-flow pair of period panties, or natural material against your skin with the cotton period panties. If you are unsure which models to choose, our period panties comparison tool compares them side by side. After giving birth, the postpartum panties range is more suitable, while athletes will find dedicated styles in sportswear for athletes.

Frequently asked questions about amenorrhea

• 01What is amenorrhea, and when is it considered an absence of periods?

  Amenorrhea is the absence of periods in a woman of reproductive age. Primary amenorrhea is when an adolescent has not had her first period by age 16, although periods normally begin between ages 10 and 15. Secondary amenorrhea is when periods stop for more than 3 months in a woman who previously had regular cycles. The MSD Manual extends this threshold to 6 months or more when cycles were already irregular.

• 02Is the absence of periods always related to pregnancy?

  No, but pregnancy remains the most common cause and the first one to rule out, including when using contraception and even when it seems unlikely. A urine test or a blood beta-hCG test can provide an answer within minutes. The other two situations in which the absence of periods is normal are breastfeeding, when prolactin blocks ovulation, and menopause, confirmed after one year without periods.

• 03What are the most common causes of secondary amenorrhea?

  After pregnancy, breastfeeding, and menopause, the most common causes are significant stress, weight loss or dietary restriction, intense athletic training, polycystic ovary syndrome, which affects 5 to 10% of women of childbearing age, excess prolactin caused by an adenoma or medication, ovarian insufficiency before age 40, and recently stopping the pill. More rarely, the obstruction is uterine, involving adhesions or cervical stenosis.

• 04Can stress really make periods disappear?

  Yes. This is known as functional hypothalamic amenorrhea: the hypothalamus pauses the menstrual cycle in response to prolonged stress, weight loss, excessive exercise, or a combination of the three. The French National Health Insurance service states that improving psychological well-being can restore periods. However, this is a diagnosis of exclusion, made only after other causes have been ruled out, and the Endocrine Society recommends an evaluation as soon as the interval between cycles consistently exceeds 45 days or in cases of amenorrhea lasting 3 months or more.

• 05What are the health risks if amenorrhea persists?

  The best-documented risk is loss of bone density, linked to estrogen deficiency, with possible progression to osteopenia and then osteoporosis and a risk of fractures. The Endocrine Society suggests measuring bone mineral density by bone densitometry in any adolescent or woman with 6 months or more of amenorrhea. The MSD Manual also mentions cardiovascular disorders among the long-term effects of estrogen deficiency. Conversely, anovulation with unopposed estrogen exposure increases the risk of endometrial hyperplasia and endometrial cancer.

• 06How is the diagnosis made, and what tests are necessary?

  The consultation begins with questions about your medical history, measuring weight and height, calculating BMI, and looking for signs such as excessive hair growth or acne. The assessment includes a beta-hCG test, followed by hormone tests: FSH, LH, estradiol, progesterone, prolactin, and testosterone if there are signs of hyperandrogenism. Anti-Müllerian hormone is tested as a second-line investigation. Depending on the case, additional tests may include an abdominal and pelvic ultrasound, a hand X-ray to assess bone age, a hypothalamic-pituitary MRI, and a karyotype.

• 07Can you get pregnant when you do not have periods?

  Yes, and this is often misunderstood. Ovulation precedes menstruation by about two weeks; it does not follow it. A woman whose cycle is restarting therefore ovulates before experiencing any bleeding to signal it. Amenorrhea is never a form of contraception, including during breastfeeding, when the return of periods is delayed but not prevented.

• 08How long without periods after stopping the pill is considered normal?

  Several weeks without periods are normal after stopping hormonal contraception while the hormonal axis resumes functioning. Assurance Maladie sets the limit at 3 months: beyond that, the situation should be medically investigated. It is then no longer simply a consequence of stopping contraception, and another cause must be sought.

• 09Can amenorrhea be treated, and what are the treatments?

  Amenorrhea itself is not treated; its cause is. Assurance Maladie is explicit: the cause must be diagnosed before any prescription, and taking a combined oral contraceptive to regulate periods only causes artificial bleeding. Depending on the diagnosis, management may involve hormone treatment, surgery in cases of obstruction, or treatment of the underlying disease. In cases of functional hypothalamic amenorrhea, the Endocrine Society advises against using a contraceptive pill solely to restore periods or improve bone density.