Why periods change after 40: normal and causes

After age 40, menstrual cycles often begin to change as menopause approaches—a period known as perimenopause. As the ovaries release eggs less regularly, and sex hormone production becomes less predictable, cycles may initially shorten slightly, then become increasingly irregular: periods may come earlier or later, sometimes be missed, and bleeding may become shorter or longer, lighter or heavier. [1]

However, being over 40 doesn't automatically mean that any unusual bleeding can be attributed to perimenopause. Intermenstrual bleeding, bleeding after intercourse, or significantly heavier or longer periods can be associated not only with changes in ovulation, but also with polyps, fibroids, adenomyosis, thyroid disease, medications, pregnancy, and, less commonly, endometrial pathology. Therefore, any new noticeable changes in bleeding patterns should be discussed with a gynecologist. [2]

In women aged 45 and over with a typical clinical picture of perimenopause, specific tests for "female hormones" are usually not necessary to confirm the transition itself: levels of follicle-stimulating hormone and estradiol vary greatly from cycle to cycle. NICE recommends diagnosing perimenopause after age 45 primarily based on age, symptoms, and cycle changes; in women aged 40-45, follicle-stimulating hormone testing may be considered if there are corresponding symptoms and changes in menstrual cycles. [3]

What happens to your cycle after 40?

The main reason for age-related changes in the cycle is the gradual reduction in the supply of follicles in the ovaries and changes in the functioning of the system that regulates ovulation. Menopause does not occur when estrogen levels begin a gradual and steady decline. It is preceded by years when hormonal activity can fluctuate greatly: one cycle may include ovulation, another without, and concentrations of estradiol and follicle-stimulating hormone can vary significantly even in the same woman in successive cycles. [4]

That is why the presentation:

"After 40, estrogen gradually declines, so periods become less frequent."

Too simplified.

In the early stages of perimenopause, some women experience shorter cycles. Later, cycles become more spaced, with missed periods occurring, and, closer to the last menstrual period, intervals typically become longer. The Menopause Society notes that at the beginning of perimenopause, periods often arrive slightly earlier than usual, and as the transition progresses, the difference between cycles can reach seven days or more; in the later stages, periods without a period can last 60 days or longer. [5]

These observations formed the basis for criteria for the stages of reproductive aging. The early stage of the menopausal transition is characterized by a persistent change in the length of successive cycles of approximately seven days or more, while a menstrual-free period of 60 days or longer is used as one of the indicators of a late transition. This is not a home diagnostic test and does not predict the exact date of the last menstrual period, but it does explain the typical sequence of changes. [6]

What period changes are most typical during perimenopause?

Almost any of the main parameters of the cycle can become less predictable. It's not just the start date of your period that changes.

What's changing?	What it might look like during perimenopause	What is especially important
Interval between periods	first shorter, then longer; individual periods are skipped	A significant new rhythm disturbance should still be discussed with a doctor.
Duration of bleeding	less or more than usual	prolonged bleeding requires evaluation
Volume	periods are lighter or heavier	Significantly heavy bleeding should not be automatically considered normal.
Regularity	adjacent cycles differ significantly	variability usually increases as the transition progresses
Ovulation	does not occur in every cycle	pregnancy is still possible
Associated symptoms	hot flashes, night sweats, sleep disturbances, vaginal dryness	help recognize the menopausal transition

[7]

It's especially characteristic that the changes don't progress in a strictly linear fashion. A woman may initially have a cycle every 23-25 days for several months, then one cycle may last significantly longer, and then the usual rhythm may return. Several months without a period may also be followed by a new period. Until 12 months without a period have passed without intervening hormonal contraception, natural menopause cannot be considered complete. [8]

Why does the cycle sometimes get shorter at first?

Early cycle shortening is one of the recognized indicators of the onset of the menopausal transition. Age-related changes in ovarian function can lead to follicle maturation and hormonal dynamics of the first half of the cycle changing even before long missed periods occur. [9]

Therefore, a woman aged 42-45 sometimes notices not delays, but the opposite:

“My cycle used to be 29 days, but now my period starts coming every 24-26 days.”

This pattern may indeed be consistent with early reproductive aging. However, if bleeding begins to occur regularly and frequently, or if extra blood appears between regular periods, this should not be automatically considered normal.

According to the current classification of the International Federation of Gynecology and Obstetrics, for most people of reproductive age, a cycle length of 24-38 days is considered normal, and bleeding lasting more than eight days is considered prolonged. However, after age 45, regularity naturally becomes significantly more variable, so formal boundaries must be interpreted in conjunction with an individual's cycle history. [10]

Why then do periods start to be delayed and disappear?

As the functional reserve of the ovaries decreases further, ovulation occurs less regularly. Some cycles become significantly longer, and sometimes the egg does not mature at all or is not released from the ovary. [11]

This creates a characteristic late pattern:

"I had my period every month → then it was two weeks late → then two normal cycles → then nothing for two months → bleeding again."

This alternation does indeed occur during perimenopause.

However, missed periods after age 40 are not evidence of perimenopause. As long as ovulation continues, pregnancy remains possible. The NHS and The Menopause Society emphasize that cycle irregularities do not mean the end of fertility, and contraception remains necessary until confirmed menopause if pregnancy is not desired. [12]

Therefore, if your period is unexpectedly late and you are considering pregnancy, the first sensible step may not be a menopause test, but a regular pregnancy test.

Why periods can become heavier after 40

Heavier periods may occur during perimenopause, but they should not be automatically assumed to be a direct and harmless consequence of estrogen surges.

Changes in ovulation frequency can alter the growth and shedding of the endometrium, the lining of the uterus. Clinically, this can manifest as irregular or altered bleeding. ACOG lists ovulatory dysfunction as one of the causes of abnormal uterine bleeding. [13]

However, research into the menopausal transition suggests that the mechanism behind heavy bleeding is more complex than simply explaining "I didn't ovulate, so I'm bleeding more." For example, in a study of 804 women aged 42-52, short and long cycles were indeed more often associated with a lack of ovulation, while heavy bleeding was more strongly associated with other factors, including fibroids and obesity. Therefore, unusually heavy periods should especially not be automatically attributed to perimenopause alone. [14]

After age 40, structural causes of bleeding—myomas, polyps, and adenomyosis—become clinically significant. The international PALM-COEIN system specifically distinguishes between structural causes of abnormal uterine bleeding—polyps, adenomyosis, leiomyomas, malignant and precancerous changes—and nonstructural causes, including ovulation disorders, coagulation disorders, endometrial disorders, and drug-induced disorders. [15]

That is why the phrase:

"I'm 47, so my heavy periods are just menopause."

May delay diagnosis of a treatable cause.

On the contrary, periods may become very scanty.

Yes. Bleeding volume during perimenopause can increase or decrease. The Menopause Society and ACOG describe lighter periods as one common transition. [16]

One month the bleeding may be normal, another month it may consist of a few days of light discharge, and then the next cycle it becomes heavier again.

If light periods are accompanied by missed periods and typical symptoms, such as hot flashes or night sweats, this fits well with the menopausal transition.

But here too, the principle of "age does not prove the cause" applies. Changes in hormonal contraception, pregnancy, significant weight loss, intense physical activity, stress, and some endocrine diseases can also alter the pattern of menstruation. [17]

Why periods can last longer

The duration of bleeding also becomes less predictable. The Menopause Society notes that during perimenopause, the number of days of bleeding can either decrease or increase. [18]

The International Federation of Gynecology and Obstetrics considers bleeding lasting more than eight days to be prolonged and classified as abnormal uterine bleeding. [19]

This doesn't mean that the disease will necessarily be detected on the ninth day. The boundary is needed primarily for a standardized description of the symptom.

Much more important is a change in one's normal cycle. If a woman has bled four or five days a week for decades and now regularly bleeds nine or ten days a week, this new pattern merits discussion with a doctor, even in the absence of pain.

Are blood clots normal after 40?

Small clots may appear during heavy menstrual bleeding, but their presence cannot determine the cause.

Clots form when blood flows rapidly enough that the mechanisms that maintain its fluid state are unable to completely prevent clotting before it exits. Therefore, a larger number or size of clots often reflects a more intense blood flow rather than a specific underlying condition.

What's more important is not the type of clot itself, but how the bleeding has changed overall: whether the protection has to be changed significantly more often, whether there are leaks at night, weakness, shortness of breath during exertion, or a significant decline in quality of life.

The modern approach to heavy menstrual bleeding is generally less focused on measuring milliliters of blood. NICE defines clinically significant heavy bleeding primarily by its impact on a woman's physical, emotional, social, and daily life. [20]

Why do some periods become more painful?

A sharp increase in pain is not one of those changes that should be automatically attributed to perimenopause alone without verification.

Menstrual sensations may vary, but new, severe dysmenorrhea—pain during menstruation—especially when combined with heavy bleeding, calls for consideration of adenomyosis, endometriosis, fibroids, and other gynecological causes.

NICE recommends that in cases of heavy bleeding and significant menstrual pain, the possibility of adenomyosis should be considered and transvaginal ultrasound should be preferred as an imaging method when clinical findings suggest it. It should also be remembered that endometriosis can cause similar pain. [21]

So the scenario is:

"I'm 46, and my periods used to be almost painless, but now every cycle requires strong painkillers."

It is best to consider it as a reason for a gynecological evaluation, rather than simply as a necessary part of menopause.

What is considered normal menopausal bleeding and what is considered abnormal bleeding?

The difference isn't always absolute, as perimenopause itself creates irregularities. But some patterns require more attention.

Change	May occur during perimenopause	Why an assessment might still be needed
the cycle became a little shorter	Yes	Very frequent bleeding may have another cause.
the cycle became longer	Yes	pregnancy and other causes of amenorrhea must be taken into account
individual periods are missed	Yes	pregnancy is possible before menopause
the bleeding became easier	Yes	usually the entire clinical picture is assessed
my periods became heavier	Yes	myoma, polyp, adenomyosis, endometrial pathology are possible
blood between periods	You shouldn't just chalk it up to age	requires discussion with a doctor
blood after sexual intercourse	does not refer to the typical variant of normal menstruation	a search for the source of bleeding is necessary
bleeding after 12 months without a period	This is no longer a normal perimenopause.	any postmenopausal bleeding should be checked

[22]

The main principle is that perimenopause increases the likelihood of irregularity, but does not eliminate the diagnosis of abnormal uterine bleeding.

Why can't everything be explained by "hormones" alone?

After age 40, two processes occur simultaneously. On the one hand, age-related changes in ovarian function actually begin. On the other hand, with age, the likelihood of detecting gynecological conditions that can alter bleeding increases.

The modern PALM-COEIN system is convenient precisely because it does not reduce the problem to a single hormonal cause.

Structural causes include:

• endometrial polyp;
• adenomyosis;
• myoma;
• hyperplasia and malignant changes in the endometrium.

Non-structural causes include:

• blood clotting disorders;
• ovulatory dysfunction;
• disorders of the endometrium itself;
• drug-induced bleeding;
• other less common causes. [23]

Pregnancy and related conditions should be considered separately, as fertility is reduced but not eliminated during perimenopause. ACOG includes pregnancy, miscarriage, and ectopic pregnancy in the differential diagnosis of abnormal bleeding in women of reproductive age. [24]

Myoma after 40 years

Fibroids can be one of the reasons why periods become significantly heavier or longer.

A myoma is a benign tumor of the uterine muscle tissue. The nature of symptoms depends on the number, size, and especially the location of the nodes. Submucous tumors, which distort the uterine cavity, are particularly likely to affect bleeding patterns.

If a structural cause is suspected, the choice of investigation depends on the clinical presentation. NICE recommends ultrasound if large fibroids or a pelvic mass are suspected, and if intracavitary polyps, submucous fibroids, or endometrial pathology are suspected, outpatient hysteroscopy is recommended as a more accurate method for examining the uterine cavity. [25]

Therefore, conventional ultrasound examination and hysteroscopy answer slightly different diagnostic questions and are not always interchangeable.

Endometrial polyps

Polyps can cause both heavier periods and bleeding between periods.

Ultrasound can detect an intrauterine mass, but if there is a high suspicion of uterine cavity pathology, hysteroscopy allows for a direct examination and, depending on the situation, a targeted removal or biopsy. This is why NICE prefers hysteroscopy for persistent intermenstrual bleeding or other signs of intrauterine pathology. [26]

This is one example of why the phrase:

"The ultrasound is normal, which means any bleeding between periods is simply due to age."

Not always sufficient.

The choice of further investigation is determined by the type of bleeding and individual risk.

Adenomyosis

In adenomyosis, tissue similar to the endometrium is present within the muscular wall of the uterus. The condition can be accompanied by heavy and painful periods, a feeling of pressure, and an enlarged uterus.

If heavy bleeding after age 40 is accompanied by new or significantly increased menstrual pain, adenomyosis is one of the causes to consider.

NICE recommends transvaginal ultrasound when clinically suspected as it is better at detecting adenomyosis than transabdominal ultrasound and is usually preferred over magnetic resonance imaging as an initial test.[27]

Thyroid gland

Thyroid dysfunction can alter your menstrual cycle, but there's no need to have every woman's thyroid-stimulating hormone levels checked just because she's turned 40 and her cycle has become irregular.

NICE does not recommend routinely testing thyroid hormones in the presence of heavy menstrual bleeding unless there are other symptoms or signs of thyroid disease.[28]

The examination becomes more justified if, for example, a marked change in weight, intolerance to cold or heat, palpitations, tremors, a significant change in energy, skin or bowel function occur simultaneously.

This is an example of a targeted approach: the test is not ordered “just in case,” but to answer a specific clinical question.

Can medications change periods?

Yes. Both hormonal medications and some non-hormonal drugs can change the nature of bleeding.

ACOG notes that hormonal contraception can cause breakthrough bleeding and noticeably alter menstrual cycles. Anticoagulants and aspirin can increase blood loss, and copper intrauterine devices (IUDs) can cause heavier periods in some women, especially after insertion. [29]

This is especially important after age 40, when a woman may simultaneously begin the menopausal transition and take new medications for other medical reasons.

Therefore, during the consultation, it is useful to inform the doctor not only about hormonal drugs, but also about all medications and supplements that are used regularly.

How to tell if you're really perimenopause

In women over 45, the combination of a changed cycle with typical symptoms often allows perimenopause to be recognized clinically, without a special “hormonal panel.”

These symptoms include:

• tides;
• night sweats;
• sleep disorders;
• vaginal dryness and discomfort;
• mood changes;
• changes in sexual desire;
• changes in the menstrual cycle. [30]

NICE recommends that in healthy people aged 45 years and over with recent onset of vasomotor symptoms and cycle changes, perimenopause should be defined by clinical presentation rather than blood tests.[31]

This is due to the fact that hormones fluctuate during the transition period. One day, follicle-stimulating hormone levels may be high, while in another cycle, they may be significantly lower. A single number cannot accurately describe a dynamic, multi-year process. [32]

And if a woman is 40-44 years old

Here the approach is a little different.

The onset of cycle changes after age 40 may indeed be perimenopause, but menopause before age 45 is considered earlier, so a doctor can make a more targeted assessment.

NICE recommends considering a follicle-stimulating hormone test in women aged 40–45 years if menopausal symptoms, including cycle changes, are present. In women under 40 years of age, if premature ovarian failure is suspected, the diagnosis should not be based on a single test – NICE recommends appropriate symptoms and two elevated follicle-stimulating hormone results obtained 4–6 weeks apart. [33]

ACOG, in its 2025 update, formulates a similar principle: Most women do not require hormonal testing during perimenopause, but before age 45, it may be used if bleeding changes occur, especially if the woman is under 40. [34]

Thus, a 42-year-old woman and a 49-year-old woman with the same complaint will not always be examined in exactly the same way.

Is it necessary to take follicle-stimulating hormone, estradiol, and anti-Müllerian hormone tests?

After 45 years of age, with typical perimenopause - usually no.

NICE specifically advises against the use of the following for the diagnosis of perimenopause or menopause in people aged 45 years and over:

• anti-Müllerian hormone;
• inhibin A;
• inhibin B;
• estradiol;
• antral follicle count;
• ovarian volume. [35]

Follicle-stimulating hormone is also not a universal test, especially if combined hormonal contraception or high-dose progestogen is used, as the result is difficult to interpret.[36]

Therefore, the commercial idea is:

"I'll get all my sex hormones checked and find out exactly how long I have left until menopause."

Does not comply with modern recommendations.

Existing studies do not allow one such panel to reliably determine the date of an individual woman's last menstrual period.

Is anti-Müllerian hormone necessary?

Not for routine diagnosis of perimenopause.

Anti-Müllerian hormone reflects certain aspects of ovarian reserve and is widely used in reproductive medicine, but NICE specifically recommends against its use to diagnose perimenopause or menopause after 45 years of age. [37]

A low result does not mean:

"Menopause will occur in six months."

A high result also does not guarantee a certain number of remaining reproductive years.

Therefore, with typical age-related changes in menstruation, a clinical history is much more useful than trying to determine status based on a single indicator.

What tests might actually be needed if your periods change?

The examination is aimed not so much at proving perimenopause, but at excluding other causes of changed bleeding.

The range of tests depends on your symptoms. Your doctor may consider:

Study	What might it be needed for?	Limitation
pregnancy test	rule out pregnancy and related conditions	perimenopause itself does not exclude pregnancy
complete blood count	assess anemia in cases of heavy bleeding	does not determine the cause of bleeding
thyroid hormones	if there are symptoms of thyroid disease	not needed by everyone
transvaginal ultrasound	evaluate the uterus, fibroids, ovaries, signs of adenomyosis	does not always accurately detect intracavitary pathology
hysteroscopy	directly examine the uterine cavity	prescribed according to clinical indications
endometrial biopsy	rule out hyperplasia, precancer, or cancer	the need and method depend on age, risk and management

[38]

For heavy menstrual bleeding, NICE recommends a complete blood count (CBC) for all patients, but does not recommend routine testing of 'female hormones' or thyroid hormones without associated symptoms.[39]

When is an endometrial biopsy needed?

This is one area where international recommendations differ slightly, and that difference is important.

The American College of Obstetricians and Gynecologists recommends endometrial tissue sampling as a first-line test for abnormal uterine bleeding in patients over 45 years of age. In younger patients, indications are strengthened by factors such as prolonged estrogen exposure without sufficient progestogen counteraction, obesity, polycystic ovary syndrome, persistent bleeding, or treatment failure. [40]

NICE takes a different approach to women with heavy menstrual bleeding. The guideline does not recommend routine blind biopsy and suggests taking an endometrial sample during diagnostic hysteroscopy in high-risk patients, such as those with persistent intermenstrual or irregular bleeding, obesity with infrequent heavy bleeding, polycystic ovary syndrome, tamoxifen treatment, or treatment failure. [41]

This doesn't mean one system is right and the other is wrong. The strategy depends on national guidelines, the nature of the bleeding, and individual risk. For the patient, the practical conclusion is much simpler: new abnormal bleeding after age 45 deserves evaluation, but the need for a specific biopsy should be determined by a physician.

When is an ultrasound examination sufficient?

Ultrasound is particularly useful when a structural cause is suspected, such as fibroids, adenomyosis, or a pelvic mass.

If adenomyosis is suspected, NICE prefers transvaginal ultrasound. If the uterus is enlarged or large fibroids are suspected, ultrasound is also an appropriate initial investigation. [42]

However, if persistent bleeding between periods is the primary concern and there is a risk of a polyp or other uterine pathology, hysteroscopy may be more informative. NICE emphasizes that it is more accurate than ultrasound in detecting intracavitary polyps, submucous fibroids, and some endometrial changes. [43]

Therefore the phrase:

"I've already had an ultrasound; there's no need to check anything else."

It is as inaccurate as the statement that every woman needs a hysteroscopy.

The study is selected for a specific diagnostic question.

What to do if your periods become very heavy

The first thing to consider is how different your bleeding is from your usual bleeding and whether it is affecting your well-being and life.

The modern definition of heavy menstrual bleeding focuses on more than just blood volume. If periods force you to cancel work or travel, regularly result in leaks, require you to change your protection at night, cause significant weakness, or significantly limit your usual activities, this is sufficient to warrant discussing the issue with your doctor. NICE emphasizes that treatment should focus primarily on improving quality of life, not on measuring the number of milliliters of blood. [44]

In cases of heavy bleeding, a complete blood count is usually assessed, as prolonged blood loss can lead to iron deficiency and anemia. The FIGO International Review highlights heavy menstrual bleeding as a significant factor in iron deficiency and iron deficiency anemia. [45]

Treatment options depend on the underlying cause, the need for contraception, other medical conditions, and the woman's preferences. Depending on the situation, a levonorgestrel-releasing intrauterine system (IUS), combined hormonal contraception, progestogens, tranexamic acid, or nonsteroidal anti-inflammatory drugs (NSAIDs) may be used; structural pathology may sometimes require specialized gynecological treatment. [46]

You shouldn't start hormonal treatment on your own just because "after 40 it's menopause" - you first need to understand the nature of the bleeding and contraindications.

When bleeding becomes an emergency

Very severe acute bleeding can result in significant blood loss and requires immediate evaluation.

ACOG recommends seeking emergency medical attention if you have to change a pad or tampon every hour for more than two hours in a row and also experience dizziness or lightheadedness, shortness of breath, or chest pain.[47]

Even without an exact count of the pads, the urgency increases:

• loss of consciousness or severe pre-syncope;
• rapidly increasing weakness;
• dyspnea;
• severe pain;
• suspicion of pregnancy against the background of significant bleeding.

In such a picture, it is more important to assess the hemodynamic state and the cause of bleeding than to determine whether the woman is perimenopausal.

Is bleeding between periods also perimenopause?

Intermenstrual bleeding should not be automatically considered a normal part of perimenopause.

ACOG classifies bleeding or spotting between periods as a pattern that is considered abnormal and requires discussion with a gynecologist.[48]

The causes may be benign - such as a polyp, hormonal contraception, or inflammation - but the nature of the symptom differs from the usual variability in the date of the onset of menstruation.

If such bleeding recurs, especially after 40-45 years, age becomes an argument for a more careful assessment, rather than ignoring the symptom.

What if blood appears after sex?

Recurring bleeding after intercourse should also not be attributed to perimenopause without an examination.

During periods of diminished estrogen levels, vaginal tissues may become drier and more fragile, so intercourse may indeed cause slight bleeding. ACOG classifies post-sex bleeding as a possible manifestation of the genitourinary syndrome of menopause. [49]

However, the source could also be the cervix, a polyp, an infection, or another condition.

Therefore, recurrent postcoital bleeding requires evaluation of the source of bleeding, even if a woman simultaneously experiences vaginal dryness and other perimenopausal symptoms.

When is your period considered to be completely over?

Natural menopause is confirmed retrospectively: after 12 consecutive months without menstruation, if the absence of bleeding cannot be explained by hormonal contraception or other intervention. [50]

Before these 12 months have passed, a long break can still end with a new menstruation.

For example:

Last period in January → bleeding again in October.

It could also be late perimenopause.

But if 12 months have passed:

Last menstrual period in January of last year → new bleeding in March of this year,

This episode is considered postmenopausal bleeding and requires medical assessment, regardless of the amount of blood. The NHS emphasizes that even a single instance of light spotting or pink-brown discharge after menopause should be assessed. [51]

Can menstruation start again after a year's break?

Once natural menopause has been confirmed, new bleeding is not considered a return to normal menstruation.

The cause is often benign, such as tissue thinning, a polyp, or hormonal therapy. However, the doctor's job is to rule out endometrial pathology and other causes.

In April 2026, ACOG updated its US guidelines for postmenopausal bleeding. For most patients, the organization now recommends including both transvaginal ultrasound and endometrial tissue sampling in the initial evaluation, a more proactive strategy than previous guidelines. [52]

The specific algorithm varies between health systems, but the internationally consistent principle is that any bleeding after 12 months of natural amenorrhea should be checked.[53]

Is it possible to get pregnant with irregular periods after 40?

Yes. Until menopause is confirmed, spontaneous ovulation is still possible.

The chances of getting pregnant decrease with age, but irregular cycles are not contraceptive. The Menopause Society points out that women in perimenopause can still become pregnant and, if they don't plan to become pregnant, should continue to use contraception until menopause is confirmed. [54]

This is especially important after several months without a period. This interval can create the feeling that reproductive function has already ended, but then ovulation can suddenly occur.

Furthermore, conventional menopausal hormone therapy is not intended to prevent pregnancy. Therefore, the choice of treatment for vasomotor symptoms and the choice of contraception are related, but not identical, issues.

Can hormonal contraception hide perimenopause?

Yes. It can alter or completely suppress the natural menstrual pattern, making it difficult to determine the transition stage based on bleeding.

The progestogen-only pill, hormonal intrauterine system (IUS), implant, or injection can make bleeding irregular or stop it completely. Combined hormonal contraception, on the other hand, can cause regular withdrawal bleeding, which doesn't indicate whether your natural cycle is continuing on its own. [55]

NICE therefore specifically warns that it may be difficult to determine the menopause in a person on hormone therapy, and that follicle-stimulating hormone testing should not be used to determine the menopause in people on combined oestrogen-progestogen contraception or high-dose progestogen.[56]

If the goal is to simultaneously control bleeding, provide contraception, and treat perimenopausal symptoms, it is best to select a regimen in consultation with your doctor.

How to prepare for a gynecologist consultation

The most useful information is not just the current day of the cycle, but the history of several months.

The Menopause Society recommends keeping a calendar or app to track your bleeding.[57]

It is useful to write down:

• the date of the first day of each menstrual period;
• How many days does the bleeding continue?
• how different it is from the previous one;
• Are there days of very intense traffic?
• Do you have bloody discharge between periods?
• Is there bleeding after sex?
• Are your periods accompanied by new or increased pain?
• whether there were hot flashes, night sweats, or significant changes in sleep;
• what contraception, hormones and other medications you are taking.

Several months of such a calendar often give the doctor more information about the stage of transition and the nature of abnormal bleeding than a random analysis of a single hormone.

What is often misunderstood

"After 40, any irregular periods are menopause."

No. Perimenopause is indeed a common cause, but irregular periods can also be due to pregnancy, medications, thyroid dysfunction, structural abnormalities of the uterus, and other conditions.[58]

"During perimenopause, estrogen only drops."

No. Hormone levels can fluctuate significantly, but estradiol can remain relatively stable until the late stages of transition. This is why single hormonal tests are poor indicators of the perimenopausal stage. [59]

"At first, periods are bound to become rare."

No. In the early stages, the cycle is often slightly shortened at first, with long intervals and skipping periods becoming more common later. [60]

"If your periods are heavy, it's simply a lack of progesterone."

This conclusion is overly simplistic. Ovulation disorders can indeed alter bleeding, but heavy periods are also associated with fibroids, adenomyosis, polyps, endometrial pathology, and other causes. [61]

"You need to take a full hormonal panel."

Generally no. NICE does not recommend the use of estradiol, anti-Müllerian hormone, and a number of other tests for routine diagnosis of perimenopause after age 45. [62]

"If the ultrasound is normal, there's no need to check for unusual bleeding."

Not always. Ultrasound examination provides a good answer to a number of structural questions, but some intracavitary changes are better detected by hysteroscopy, and endometrial pathology, if there is an appropriate risk, is assessed histologically. [63]

"After several months without a period, pregnancy is impossible."

No. Irregular ovulation can continue until menopause. [64]

Practical algorithm

If your cycle changes slightly after age 40, with periods coming earlier or later, or skipping periods, and hot flashes or night sweats occurring simultaneously, perimenopause is a likely explanation. This is especially common after age 45. [65]

If you are 40-44 years old, menopausal transition is also possible, but your doctor may be more proactive in assessing early menopause and may use follicle-stimulating hormone testing when appropriate. [66]

If there is an unexpected delay and pregnancy is possible, it should be ruled out - irregularity of perimenopause is not a contraceptive. [67]

If your periods become significantly heavier, longer, more painful, or if bleeding occurs between periods or after sex, you should consult a gynecologist to determine whether the cause is truly just the menopausal transition. [68]

If bleeding is heavy, it is useful to check the complete blood count to assess for anemia; further investigations - ultrasound, hysteroscopy or biopsy - are chosen based on age, type of bleeding and risk factors. [69]

If 12 months have passed without a natural menstrual period, any new vaginal bleeding requires evaluation and should no longer be dismissed as just another irregular period.[70]

Key points from experts

Esther Eisenberg, MD, MPH, is an obstetrician-gynecologist and reproductive endocrinologist, professor emeritus at Vanderbilt University Medical Center, former medical officer and director of the Fertility and Infertility Program at the National Institute of Child Health and Human Development, and a fellow of the American College of Obstetricians and Gynecologists. Her official ACOG profile lists reproductive aging among her areas of specialization. [71] In an ACOG opinion update released in February 2026, Dr. Eisenberg explains that a change in menstrual patterns in a woman's 40s is often the first sign of perimenopause, but the presence of irregular periods alone does not rule out other causes, and changes in bleeding should be discussed with a gynecologist. [72]

Stephanie S. Faubion, MD, MBA, is a professor and chair of the Department of Medicine at Mayo Clinic in Florida, director of the Mayo Clinic Center for Women's Health, and medical director of The Menopause Society. In a Mayo Clinic white paper, she emphasizes that the menopausal transition is accompanied by large fluctuations in estrogen, and cycle changes can include lighter or heavier periods and shorter or longer intervals. At the same time, the paper highlights prolonged, intermenstrual, and very frequent bleeding as a reason for medical evaluation, rather than simply "normal menopause." [73]

Faubion has also specifically addressed the issue of under-recognition of abnormal uterine bleeding during the menopausal transition: in The Menopause Society's submissions, she notes the need to better inform women about the possibility of prolonged and heavy bleeding and its consequences, including fatigue.[74]

Monica M. Christmas, MD, FACOG, MSCP, is an obstetrician-gynecologist, associate professor at the University of Chicago, director of the Menopause Program and Center for Women's Integrated Health, and associate medical director of The Menopause Society. Her clinical areas include menopause, irregular menstruation, abnormal uterine bleeding, fibroids, and endometrial pathology. [75] In The Menopause Society's educational materials, she defines perimenopause as a period when changes in the frequency and volume of menstrual periods occur due to unpredictable ovarian hormonal function and increasingly irregular ovulation. [76]

Frequently Asked Questions

Is it normal that after 40 the cycle becomes shorter?

Yes, this can be an early sign of perimenopause. At the beginning of the transition, many women experience slightly shorter cycles, and long missed periods become more common later. [77]

Can a 42 year old's cycle become irregular due to perimenopause?

Yes, it can. But before age 45, the doctor often takes other causes into account and, in the appropriate clinical context, may consider determining follicle-stimulating hormone. [78]

Why do I get my period twice a month after 45, and then not for two months?

This may reflect increasingly less predictable ovulation during the menopausal transition. However, very frequent, prolonged, or intermenstrual bleeding requires evaluation. [79]

Is it normal for my periods to become heavier?

Heavier bleeding is common during perimenopause, but new heavy bleeding should not be considered automatically normal. Fibroids, polyps, adenomyosis, and endometrial pathology can also cause this pattern. [80]

Why did my periods start to last longer?

This may be part of a changed ovulatory pattern. However, bleeding lasting more than eight days is classified by FIGO as prolonged and deserves evaluation, especially if it was previously significantly shorter.[81]

Do I need to take estradiol tests?

After 45 years of age, with typical perimenopause, this is usually not the case. NICE does not specifically recommend the use of estradiol to establish perimenopause or menopause in this age group. [82]

What about follicle-stimulating hormone?

After 45 years of age, it is usually not necessary for the typical picture. At 40-45 years of age, it can be considered with appropriate symptoms and cycle changes. [83]

Is anti-Müllerian hormone necessary?

For routine determination of perimenopause after age 45 – no. NICE does not recommend the use of anti-Müllerian hormone for this purpose. [84]

How do you know if you've already gone through menopause?

Natural menopause is established after 12 consecutive months without menstruation, unless the absence of bleeding is explained by hormonal contraception. [85]

Is it possible to get pregnant if your period comes once every two to three months?

Yes. Ovulation during perimenopause is unpredictable, but it can occur. [86]

Should all women over 40 have an ultrasound if their cycle changes?

No. The need for ultrasound is determined by the nature of the bleeding, examination and the likelihood of structural pathology. [87]

Should everyone over 45 have a biopsy?

Not all countries use the same algorithm. ACOG recommends endometrial screening for abnormal bleeding in patients over 45 years of age as a first-line investigation, while NICE recommends selective biopsy during hysteroscopy in high-risk patients with heavy bleeding. [88]

What should you do if your period disappears for five months and then returns?

Until a full 12-month period is complete, this scenario may be consistent with late perimenopause. However, if bleeding is unusually heavy or has other worrisome features, it still needs to be evaluated. [89]

What to do if bleeding appears after a year without a period?

See a doctor. This is postmenopausal bleeding, and even a single small spotting should be checked. [90]

When does heavy bleeding require emergency care?

If you have to change your pad or tampon every hour for more than two hours in a row and also experience shortness of breath, chest pain, severe dizziness, or lightheadedness, ACOG recommends seeking emergency care.[91]

Main

After age 40, menstrual patterns often change due to the menopausal transition. The primary mechanism is not a gradual "disappearance of estrogen," but a gradual depletion of ovarian reserves, increasingly irregular ovulation, and significant fluctuations in hormonal activity. Therefore, cycles may initially shorten, then become chaotic, and later, increasingly miss periods; the duration and volume of bleeding may also change. [92]

But perimenopause is a probable explanation, not a universal diagnosis, for any bleeding after 40. It's especially important to check bleeding between periods, after sex, new, very heavy or prolonged periods, and a marked increase in pain. After age 45, abnormal uterine bleeding also requires more careful attention to the condition of the endometrium. [93]

In the typical picture after age 45, a special hormonal panel is often ineffective: the diagnosis of perimenopause is usually established based on age, cycle pattern, and symptoms. It is much more useful to keep a bleeding calendar for several months and, if necessary, direct testing to a specific possible cause. [94]

And there is a clear line after which the word “period” is no longer correct to use: if after 12 months without a natural menstruation, blood appears again, this is postmenopausal bleeding and should be examined. [95]