A woman can only produce 400 eggs in her lifetime? Whoever uses them up first will age first?

I believe many people have heard this saying: women only have 400 eggs in their lifetime, and when they have all been released, they will go through menopause and their ovaries will be "retired". To put it bluntly, whoever releases all the eggs first will age first.

This has caused many women to worry: if menarche is early or the menstrual cycle is short, according to this conclusion, won’t they go through menopause earlier and age faster than their peers? Some women also believe that late menstruation is a sign of good health.

So what is the real situation? Let’s talk about it today.

Do women really only have 400 eggs in their lifetime?

First of all, we have to make it clear that no one has yet counted the number of ovulations of every woman in the world in her lifetime to come up with an average. This workload is too much. The conclusion of 400 is just a guess based on a "given premise". This given premise includes three average data of Chinese women:

Menarche at 12 years old

Menstruation stops at 49

One egg is released every month

Then the total number of ovulations is 12 × 37 = 444, which is the origin of the saying that "a woman will ovulate 400 to 500 eggs in her lifetime." But just as the average salary cannot represent individual income, this average number of ovulations cannot summarize the true situation of each woman.

If menstruation comes early, stops late, or the menstrual cycle is short, and the number of eggs released each year is greater than 12, then the number of eggs released in a lifetime will be far greater than 400.

Copyright images in the gallery. Reprinting and using them may lead to copyright disputes.

Some people may say that there may be differences among individuals, but there is always an upper limit to the number of eggs, only a few hundred, and once they are all released, that's it.

In fact, this is also inaccurate. The number of eggs stored in a woman's body is much greater than many people think.

When a woman is still a five-month-old fetus in the womb, the number of primordial follicles in her body has reached 7 million. Although this number will continue to decline with age, when a woman enters puberty, between the ages of 10 and 15, the number of primordial follicles will still remain between 300,000 and 400,000.

During each menstrual period, the ovaries will select 10 to 15 primordial follicles and cultivate them into antral follicles. In the end, only one (occasionally two or more, but the probability is very low) will become a mature egg. If it does not combine with sperm, it will be absorbed by the body. At this time, the endometrium, which has thickened in order to nurture the fertilized egg but is ultimately useless, will be exfoliated, resulting in menstruation.

As long as the ovaries function normally, women will release an egg in each menstrual cycle and have regular menstruation. What really stops women from ovulating is not the lack of egg reserves, but the aging of the ovaries with age, which is a normal physiological phenomenon like the aging of other organs and tissues in the human body, not premature ovarian failure caused by short menstrual cycles and excessive ovulation. Many marketing accounts say that "the ovaries are retired because the eggs have been released", which is just a reversal of cause and effect.

People with short menstrual cycles tend to reach menopause earlier?

You may have noticed that women's menstrual cycles vary in length. So will those with short menstrual cycles experience menopause earlier? Let me first state the conclusion. There is no direct correlation between the length of the menstrual cycle and the early or late menopause.

Copyright images in the gallery. Reprinting and using them may lead to copyright disputes.

Normally, the menstrual cycle starts with the first day of the last menstrual period and ends on the day before the next menstrual period. In order, the menstrual cycle is mostly divided into three stages: the follicular phase (before ovulation), ovulation, and the luteal phase (after ovulation).

During the follicular phase, the ovaries release estrogen and the primordial follicles continue to develop. When one of the follicles develops into an egg and is discharged, the original follicle wall will gradually collapse and become a yellow gland-like structure rich in blood vessels, which is the corpus luteum. While synthesizing estrogen, the corpus luteum also produces progesterone, which further thickens the endometrium. If the egg does not combine with the sperm, the corpus luteum will atrophy, and the endometrium that loses the support of estrogen and progesterone will also fall off, causing bleeding. At the moment of bleeding, the primordial follicles will also begin to develop synchronously, which means that a new menstrual cycle has begun.

It is worth noting that the ovulation phase lasts about 16 to 32 hours, while the luteal phase is often fixed at 14 days. Therefore, it is actually the follicular phase, that is, the speed of egg development, that determines the length of the menstrual cycle.

The speed of egg development varies from person to person, but as long as the menstrual cycle is maintained between 21 and 35 days, it is normal.

As we mentioned earlier, the number of follicle reserves in women's bodies is sufficient. As long as the ovarian function is normal, women will have normal menstruation and ovulation. There is no short menstrual cycle, which will cause the eggs to be released prematurely and eventually lead to early menopause.

According to statistics, the average menopause age of Chinese women is 49 years old, and early menopause, which is medically recognized, often occurs before the age of 40, which is called premature ovarian failure, that is, premature failure of ovarian function. According to current research results, the cause of premature ovarian failure is still unclear. It may be inherited from the family or there may be problems with the immune system, such as systemic lupus erythematosus. However, it does not mean that the shorter the menstrual cycle, the higher the risk of premature ovarian failure. Changes in the menstrual cycle are a reflection of ovarian function, not the cause of abnormal ovarian function.

The shorter the menstrual cycle, the faster you age?

There is also a saying that the shorter the menstrual cycle, the faster the ovarian failure, so you will look older faster. In fact, ovarian failure does have a certain relationship with human aging.

The ovaries are important organs that secrete estrogen in women. When the ovaries age and atrophy, the secretion of estrogen will also decrease, which will cause aging of the reproductive system, organs throughout the body, and even the skin and hair, making people look older.

But as we have said above, people with short menstrual cycles will not have their eggs released prematurely, nor will this affect the function of the ovaries in a counterproductive way.

The length of the menstrual cycle is just a normal physiological phenomenon that varies from person to person. It is affected by many factors, such as pregnancy, endocrine disorders, or irregular lifestyle.

What can really reflect whether the ovaries are aging faster is whether there are obvious changes in the menstrual cycle. If you find that the menstrual cycle is suddenly shortened by many days compared to before, and it is not just a rare occurrence, then you need to be alert.

From youth to old age, from the panic of the first visit to the continued caution after years of getting along, menstruation not only accompanies every woman through every stage of life, but also directly reflects the mental and physical health of women.

What is important is how to understand it scientifically, not to be overly afraid, nor to be overly careless. Adhering to a regular schedule and a good attitude to ensure its regular arrival will truly determine your health status.

References

[1] Widmaier, Eric P.; Raff, Hershel; Strang, Kevin T. Vander's Human Physiology: The Mechanism of Body Function 12th. New York, NY: McGraw Hill. 2010: 555–631. ISBN0-077-35001-4.

[2] Menstruationandthemenstrualcyclefactsheet.OfficeofWomen'sHealth.December23,2014[25June2015].

[3] KarapanouO,PapadimitriouA(September2010)."Determinantsofmenarche".ReproductiveBiologyandEndocrinology.8:115.

[4] DiazA, LauferMR, BreechLL (November2006). "Menstruationingirlsandadolescents:usingthemenstrualcycleasavitalsign".Pediatrics.118(5):2245–2250.

[5] Women'sGynecologicHealth.Jones&BartlettPublishers.2011.p.94.ISBN9780763756376.

[6] DeeUnglaubSilverthorn.Humanphysiology:anintegratedapproachThirdedition.SanFrancisco:Pearson/BenjaminCummings.2004:Chapter26:ReproductionandDevelopment,andChapter23Endocrinecontrolofgrowthandmetabolism.ISBN978-0-13-102015-3.

[7] Chen Ying, Yu Qi. Age and ovarian function: understanding of ovarian aging[J]. Chinese Journal of Practical Gynecology and Obstetrics, 2017, 33(01): 68-70.

[8] He Zhong, Lin Shouqing, Chen Rong, et al. Menstrual changes during ovarian aging[J]. Journal of Peking Union Medical College, 2016, 007(002): 81-87.

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Wu Zhaodi, popular science creator

Reviewer: Lan Yibing, deputy chief physician, Department of Obstetrics and Gynecology, Zhejiang University School of Medicine