Menopause Math: Can You Predict the Age of the Menopause?

Menopause is a physiological period referring to the cessation of the menstrual cycle. However, it is not a sudden stop, and this transition happens gradually. With increasing life expectancy, one may wonder how much reproductive window they have left. Let's find answers to the question of whether it is scientifically possible to calculate or estimate the natural menopause age.

What is the average age of menopause?

Generally, perimenopause changes start around the age of 45. Natural menopause typically occurs, on average, between the ages of 45 and 56. In 5% of women, the menopausal age is between 40 and 45, which is considered early menopause. In rare cases (1%), menopause could be diagnosed younger than 40, defined as premature menopause.

However, these numbers are affected by multiple factors, such as one's genetics, upbringing, adult lifestyle, and medical conditions.

Body signals predicting menopause

One of the perimenopausal signs is the change in the menstrual cycle pattern. First, periods get more frequent; then, the length between two periods gets more prolonged than usual. Eventually, cycles stop altogether.

In addition, several physical clues may indicate the transition period. These symptoms include hot flashes, vaginal and skin dryness, mood changes, sleep problems, night sweats, chills, slowed metabolism, and weight gain. However, the definite diagnosis is the absence of periods over the last 12 months.

What impacts your menopause start?

Women's egg cells start their journey before they are born. Around the 20th gestational week of their life, women have the maximum number, around 6 million, of follicles. Follicles are fluid-filled sacks in the ovaries, and each follicle contains an undeveloped egg cell. From the 20th week of one's fetal life on, women lose follicles. Girls are born with about one million follicles and start puberty with approximately 400,000. Starting from puberty, around 50 follicles enter the growth cycle daily, which should be enough for approximately 400 menstrual cycles in one's lifetime. This process lasts until the ovarian reserve is depleted, and deficiency of estrogen, which is produced by the ovaries, leads to menopausal symptoms.

The number of follicles, also known as ovarian reserve, might be affected in every step of life: before birth, before reaching puberty, and during the reproductive years. Several factors affect how fast the follicular reserve is depleted. The effect of environmental and demographic factors was investigated in different studies, but no general agreement exists on their effects.

How can genetics influence the menopause age?

Human genetics is one of the factors affecting the menopausal age. Changes in chromosomes 13, 19, 20, and X affect the reproductive period. Around 300 genes are determined to affect the menopause age.

The average menopause age also differs between races and ethnicities. Hispanic and African American women experience early and premature menopause more than European and White American women.

Data from the UK Breakthrough Generations Study source shows that the odds of getting early menopause are 5–6 times higher if one's mother or non-twin sister had an early menopause. Similarly, if a mother or non-twin sister had late menopause, the odds of having late menopause are six and two times higher, respectively.

Can lifestyle affect menopause age?

Effects of lifestyle factors are commonly implicated in reducing the menopause age. Individual studies from several cohorts report significant environmental and lifestyle factors.

Here are some factors associated with an average lower menopausal age:

• Being born to a mother who smoked during pregnancy
• Upbringing in a lower social class
• Experiencing early-life malnourishment
• Being breastfed for less than one month
• Parental divorce or absence during childhood

In addition, here are factors associated with reduced risk for early menopause:

• Later first menstruation (after 16).
• Irregular menstrual cycles.
• Parenthood: at least one pregnancy lasting longer than six months and increasing number of pregnancies.
• Later age at first pregnancy.
• Breastfeeding.
• Oral contraceptive use.
• Moderate, but not strenuous, exercise after 30s.
• High-calorie, healthy fat, and protein diet.
• Refraining from the vegetarian lifestyle until the age of 40.
• Moderate alcohol consumption in the early 30s.
• Refraining from smoking. Even cessation of smoking is beneficial.

Can certain medical conditions influence menopause age?

In some conditions, such as surgical removal of one or both ovaries, chemotherapy, and radiation, for childhood and adult year cancers, treatments reducing estrogen effect also may lead to menopausal changes. Also, low-level lead accumulation in the body reduces the average menopause age by 1.21 years.

Polycystic ovary syndrome (PCOS) is a condition occurring with irregular menstrual cycles. Hence, it is shown that PCOS delays the menopausal age.

Can you in any way predict menopause age?

Despite the year-long attempts, the exact menopausal timing can not be predicted. However, the period leading to the cessation of periods could be diagnosed with specific symptoms and some laboratory assessments.

Is the menopause age calculator a myth?

It is highly tempting to generate an algorithm to calculate, or in the best case, to estimate the years left in the reproductive period. Despite several study attempts, no reliable tool exists. The most plausible explanation for the lack of such a tool is the absence of a scientifically-approved biomarker or parameter that could precisely correlate with menopause time.

For example, a Finnish study employing two statistical models identified the most useful factors to take into consideration to calculate the natural menopause age: estradiol and follicle-stimulating hormone levels, the length of the menstrual cycle, smoking, education, and contraceptive hormone use were among the suggested parameters. At the same time, these are statistical models to give insight to clinicians, and there is no clinically-proven algorithm for precise calculations.

Can a healthcare provider predict menopause age?

Hormonal evaluation and ultrasound assessment may give an idea of the current state of one's reproductive capacity.

In the ultrasound, the size of ovaries and the number of growing (antral) follicles could be measured. A study of >450 women reports that women with four or fewer antral follicles have a doubled risk of entering natural menopause in the following seven years. However, the evidence level of these studies is low, and antral follicle count is considered inadequate to estimate the natural menopause age.

In the hormonal analysis, follicle-stimulating hormone (FSH) levels are measured higher ten years prior to menopause. Also, inhibin A and inhibin B levels will decline in this period. However, these parameters are not reliable predictors of menopausal age.

Anti Mullerian Hormone (AMH) is produced in the ovaries and is correlated with the number of remaining potential egg cells. Hence, it is becoming a potential candidate to measure ovarian reserve. However, AMH measurement on the appointment day may weakly predict menopausal age. A study from a longitudinal AMH measurement suggests that repeated AMH measurement over time might be a potential tool, but the precision of the tool is concerning for women younger than 45.

Can menopause be delayed?

Considering the factors implicated in early menopause or lower menopausal age, modifiable lifestyle factors could be a target to delay the age of natural menopause.

• A healthy diet with required calorie levels, including healthy fats and protein, may prevent early menopause.
  
• A healthy lifestyle, with regular night sleep and a moderate amount of exercise, is also a positive contributor.
  
• Refraining from smoking positively affects the process.
  

How to manage menopausal symptoms?

Physical symptoms starting in the perimenopausal period may continue in the postmenopausal period. The length of this period varies for every woman. Hormone therapy with estrogen replacement is the most effective treatment of menopausal symptoms. Another FDA-approved treatment for vasomotor symptoms is paroxetine mesylate, which is a non-hormonal medication.

Talk to your doctor to evaluate the most suitable treatment for you and your health needs.

Overall, menopause represents a natural phase of life, and cultivating a healthy lifestyle from early stages could influence the timing of menopause. Incorporating moderate exercise, maintaining a balanced diet, and avoiding smoking may lay the groundwork for an extended reproductive lifespan.