Genetics

It has been observed that mothers and daughters tend to get their menopause at more or less the same age. This is because all women are born
with a finite number of follicles that are determined genetically. Menopause occurs when this stock of follicles are exhausted at the end of the reproductive life.

It has been estimated that there are about 7 million primary oocytes or primary follicles in the ovaries of a 24 week old female fetus. These
decrease to about 2 million at birth. Of these, only about 500 follicles develop into mature Graafian Follicles from puberty to menopause. The rest are lost through degeneration.

Pregnancy and breastfeeding

It is controversial whether pregnancy and breastfeeding affect the age of menopause. While many scientists say that it does not, may others have come to the conclusion that the age of onset of menopause is affected by the number of pregnancies a woman goes through, and the duration of breastfeeding.

The age of menopause depends to some extent on whether or not a woman ovulates (releases an ovum) every month. During pregnancy, that is for 9 months, there is no ovulation. Normally, at least 5 -6 follicles develop in each menstrual cycle during the non-pregnant state. So, each pregnancy means that these follicles remain in excess in the ovaries. A woman who has been pregnant more often will thus have a larger stock of follicles in her ovaries, and will thus menstruate for a longer time.

Ovulation is also arrested in some women during the first 5 - 6 months of active breastfeeding. So, pregnancy and breastfeeding are likely to delay the onset of the age of menopause.

Birth Control Pills

Birth control pills prevent pregnancy by suppressing the ovaries and preventing ovulation. The hormones that they contain blocks the process of oocyte maturation. Ovulation is thus prevented every month. This helps in preventing the decrease in the number of oocytes in the ovaries.

One important factor that should be noted is that lack of ovulation does not prevent the aging of oocytes within the ovary. Over time, oocytes will continue to be lost due to aging and degeneration, even when there is no ovulation, as in pregnancy, breastfeeding and taking of birth control pills.

The number of follicles thus `saved' by these processes is a tiny fraction of the total number of follicles in the ovary. So, whether the age of onset of menopause bears any relation to pregnancy, breastfeeding or birth control pills has not yet been confirmed.

General health

Women who have a poor general health, are undernourished, or have suffered from chronic illnesses like tuberculosis, sarcoidosis or thyroid problems are likely to get their menopause earlier. Cancer and subsequent chemotherapy or radiotherapy can also cause the age of onset of menopause to be earlier than normal.

Ethnicity

Women with the same ethnic background get their menopause at about the same time. For example, Japanese women are known to get their menopause
later than women with African ancestors. But this is probably because of a similar genetic component.

Other factors

Stress, obesity and environmental factors can all affect the age of onset of menopause. It has even been suggested that climactic conditions can also affect the average age of onset of menopause, since women of colder climates generally get their menopause at a later age than women of tropical climates.

So, the average age of onset of menopause can vary from woman to woman and from community to community, depending on various factors, of which
genetics and nutrition is the most important.

To know more about menopause, please see .