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Menstrual cycle changes with age


Menstruation occurs once a month. Some of you may feel that your period is getting faster
as you get older, in your 30s and 40s, compared to when you were young.
In fact, it has become clear that the menstrual cycle changes with age.

What is the normal menstrual cycle?

The period from the start of menstruation (menstruation) to the day before the start of the
next menstruation is called the “menstrual cycle”.
If you have a cycle of “once every 25 to 38 days”, it is said to be normal.
Also, you may be worried if your period differs from month to month, such as “Last month,
my period came on the 30th, but this month, my period started 25 days later …”. However,
menstruation depends on lifestyle-related habits such as sleep, stress, and fatigue, so there
may be some discrepancies.
If the deviation is within 6 days, it is considered to be within the normal range.

Menstrual cycle differs by 3 days between 20s and 40s

However, the definition that “the normal menstrual cycle is 25 to 38 days” actually refers to
data in the United States in the 1950s. Moreover, the survey in the United States had a small
number of research subjects (650), the accuracy is questionable, and the times, races, and
environments are different from now, so the results may be different from those of modern
Japanese women. There is also sex.
Therefore, the research team of the National Center for Child Health and Development and
MTI Co., Ltd., which provides the health management application “Luna Luna” for women,
conducted an analysis based on the information from about 300,000 people registered on
“Luna Luna”. As a result, it has become clear that the menstrual cycle changes with age.
Specifically, the menstrual cycle gradually became longer from the teens to the 20s,
reaching the longest at the age of 23 with an average of 30.7 days. After that, it gradually
became shorter from the 30s to the early 40s, and at the age of 45, it became the shortest
with an average of 27.3 days. After that, it gradually became longer.
The menstrual cycle differed by an average of 3 days between the 20s and 40s.

Irregular menstruation (abnormal menstruation): What is the guideline for consultation?

A shortening or lengthening of the menstrual cycle can cause concern, but it may be a
natural change with age.
However, when the menstrual cycle is too short or too long, or the menstrual period is too
short or too long, there may be some hidden hormonal imbalances or gynecological illness.
If any of the following are true, it is considered to be “menstrual disorder (irregular
menstruation)”. We recommend that you visit the gynecology department (obstetrics and
gynecology department).
・ Menstrual cycle is less than 24 days (frequent menstruation)
・ Menstrual cycle is 39 days or more (oligomenorrhea)
・ You are not pregnant, but you haven’t had your period for more than 3 months (secondary
・ Menstruation ends within 2 days (hypomenorrhea) or lasts for 8 days or more
At the “Takanawa Ladies Clinic” of Medical Prime Takanawa, doctors specializing in
gynecologic cancer and perinatal care will be available. If you have any concerns, please
feel free to contact us.
At “Hatchobori Sato Clinic” in Medical Prime Shinkawa, the deputy director (female doctor)
who has many years of experience in gynecology and obstetrics, mainly in university
hospitals, will respond. If you have any concerns, please feel free to contact us.
First-time patients may be hesitant about gynecological visits.
Medical Prime Nihonbashi Kodenmacho’s “Higashi Nihonbashi Ladies Clinic” includes a
checklist item “I don’t want to have a pelvic examination” on their primary questionnaire. If
you check this, we will explain the possible illnesses and symptoms from the patient’s story
without conducting a pelvic examination. Please feel free to contact us.

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