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Your biological clock is ticking, but when will menopause strike?

As more and more women wait until their 30s to start having children, infertility is becoming an increasing issue. We’ve all heard the saying that the “biological clock is ticking”. However, it’s difficult to know when the biological clock will strike menopause, and related to that, when fertility will begin to decline.

The average woman becomes infertile at age 41, about 10 years before menopause, and can wait until her 30s to have a child. This isn’t true for every woman though; a proportion will experience menopause earlier than most, and these women also experience the 10 or so years of premenopausal infertility early.1

Approximately 5% of Caucasian women experience menopause before 45 years of age (early menopause), and thus become infertile at around age 35. Approximately 1% of these will pass menopause before they reach 40 years of age (premature ovarian failure) and so will become infertile before they even turn 30.1

Being able to forecast the age at which to expect menopause when a woman is in her early 20s would be incredibly valuable to making decisions about when to start a family. Unfortunately, tests which predict the age of menopause early in life are not yet available. Currently the age of menopause cannot be predicted until the hormonal changes which lead to infertility and menopause have already begun.1 That’s already too late for women who want to have kids.

However, a variety of factors related to a woman’s genes and lifestyle influence when she is likely to experience menopause. Knowing which factors influence menopausal age, and in which direction, may help women determine whether they are likely to enter menopause early, and thus if they need to get a move on before their biological clock strikes menopause.1

Menopause isn’t a light switch, the transition can take over a decade

Menopause is the cessation of menstrual cycles and is diagnosed when a woman has not experienced menstrual bleeding for > 12 months.2 It occurs due to the gradual loss of eggs from a woman’s ovaries throughout life. The rate at which eggs are lost from the ovaries increases in the 10 years prior to menopause, which occurs only when the number of eggs in the ovaries falls below a threshold level of 1,000.1

As the number of eggs deplete, the amount of oestrogen the ovaries produce also reduces.2 Amongst other things, oestrogen regulates the menstrual cycle, and when too little oestrogen is produced by the ovaries… no more menstrual periods.3 But it doesn’t happen instantly. Infertility occurs approximately 10 years prior to the final menstrual period,1 and hormonal changes which trigger changes in menstrual cycle length and the regularity of menstrual bleeding generally go on for 4–5 years before a woman’s final menstrual period.4

Signs that your menopause has begun

Menstrual bleeding becomes less regular when production of oestrogen in the ovaries declines, and in the early stages of the menopausal transition (that period where oestrogen production is declining and causing irregularities that often go on for years5) the length of the menstrual cycle varies by > 7 days from its usual length of 21–35 days.2 Over time the cycle varies more substantially and women may ‘miss’ a period. When menstrual bleeding is separated by periods of more than 60 days, a woman has entered the late stage of the menopausal transition. The final menstrual period is approaching.2

Most women have probably wished, from time to time, that their menstrual bleeding would just ‘go away’. Even without premenstrual syndrome (PMT), period pain and the inconvenience of the monthly visit, we could do without the expense of all the necessary sanitary gear! Unfortunately the cessation of menstrual bleeding at menopause isn’t all “silver lining”. For some women, particularly those who experience it early, menopause carries with it a dark “cloud” of realisation that their fertile years are behind them. That being said, for women who have already had children, despite sometimes difficult menopausal symptoms, the final menstrual period can signal the start of a new phase in life.

Symptoms to expect

While irregularities in the cycle are typically the first signs of approaching menopause,2 unpleasant symptoms of menopause typically begin in the late menopausal transition while menstrual bleeding is still occurring irregularly.6 Before you’ve even done away with your menstrual bleeding, you’ll probably have your first hot flush.6

Hot flushes are the most common symptom experienced by menopausal women6 and their name pretty much sums them up. The body, beginning with the face and spreading downwards, heats up, causing flushing and sweating.7 Although sometimes referred to as hot flashes, they certainly don’t go away in a flash. Most women experience hot flushes for 2–6 years,8 and some for decades.10

Mood swings, or to use the politically correct term, the psychological changes of menopause, may also occur around the time of menopause.11 Other symptoms include sexual changes,11 sleep difficulties,12 and skin changes.13

So when should a woman expect to experience the ‘joys’ of no more periods? What influences the timing?

Genetic predictors

Women experience the beginning and end of menstruation at different ages and genes have been shown to influence the timing of both the start and finish of a woman’s reproductive life.14 Women whose mothers (and grandmothers) experienced early menopause are more likely to go through menopause early in their life, while those whose mothers entered menopause late, are also likely to follow suit.1 Studies which show differences in the age of menopause for women from different ethnic groups (Hispanic women experience menopause earlier than Caucasian women, who experience menopause earlier than Japanese women), also indicate that genes influence age of menopause.15

A considerable amount of research has been conducted in recent years, trying to determine which genetic components affect a woman’s age at menopause. These genetic differences occur due to single nucleotide polymorphisms (SNPs).1 Nucleotides are the building blocks of DNA. There are four different types of nucleotides, and every piece of DNA is made up of different sequences of these four nucleotides. From person to person, the same region of DNA will typically contain the same sequence of DNA. When a single nucleotide change disrupts this typical sequence, it is referred to as a single nucleotide polymorphism. While most SNPs have no effect on a person’s growth and development, some influence a person’s risk of developing a disease (e.g. diabetes) or experiencing a certain developmental pattern (e.g. experiencing menopause earlier or later than is usual).16 

Research has identified several SNPs which influence the risk of early menopause.1,14 While testing for these genes in women in their 20s is not yet practical, in the future tests which look for SNPs may be developed to enable women to predict when their biological clock will strike menopause.1

Lifestyle predictors

In the meantime, an educated guess, informed by aspect of the woman’s lifestyle known to influence age at menopause, is the only available ‘test’. So women who want to ensure they have babies before their ovaries retire need to pay particular attention to how they live. A woman’s lifestyle has a significant influence on the timing of her menopause and it’s necessary to consider smoking, diet and exercise, the number of babies she’s had and whether or not she has used hormonal contraception, when trying to determine when menopause is most likely to occur.


Smoking
Smoking is one aspect of lifestyle that’s received quite a bit of attention in studies about women’s age at menopause. Similar to the evidence showing a range of negative health effects of smoking, evidence that smoking affects the timing of menopause is conclusive. On average those who smoke experience menopause 2 years earlier than those who don’t.10

Smoking later in life is most likely to lead to early menopause; women who are still smoking as the menopausal transition begins, are most likely to be experiencing the changes earlier than normal. In one study, being a current smoker increased the likelihood of early menopause (before age 45) by 1.59 times.17 However, even those women who have smoked in their 20s and 30s, only to give up before the age of expected menopause onset, may have an increased risk of experiencing early menopause. Some evidence suggests that the more a woman smokes the greater her risk of early menopause.17

The relationship between passive smoking and early menopause is less clear. While some studies have reported women exposed to other people’s cigarette smoke experience menopause early, other have reported passive smoking does not affect the timing of menopause.17 The evidence for the effect of maternal smoking on her unborn daughter is more clear. Amongst non-smokers, those whose mothers smoked during their pregnancy had an earlier age of menopause compared to those whose mothers did not smoke.18


Diet and exercise
What a woman eats and how much she exercises also influence the timing of her menopause. Meat eating may protect against early onset of menopause; one study showed that vegetarian women experienced menopause earlier compared to non-vegetarian women.19 Moderate alcohol intake and high caffeine intake appear to increase the likelihood of experiencing menopause later in life,10 although for other health reasons, consuming too much caffeine10 and alcohol are not recommended.20

The relationship between levels of exercise at various points in life and the age of menopause is not yet well understood, although several studies have reported associations. Amongst a group of Chinese women, moderate-high intensity exercise during adolescence or adulthood was associated with menopause later in life than lower levels of exercise.21 In a group of British women, regular strenuous exercise was also associated with being older at menopause.19

Diet and exercise both affect weight and body mass index (BMI). There is also evidence that weight and BMI influence age of menopause. In a large British study higher weight and BMI were associated with older age at menopause, as was gaining weight between the ages of 20 and 40.19 This is just one more reason to maintain a healthy weight; being overweight is associated with a host of other health risks including diabetes and hypertension.22

 

Menopause image

For more information about how your diet and your exercise habits can influence menopausal symptoms, see Eating and Exercising Your Way Through Menopause.

 

Reproductive history
Evidence suggests that women who have never had children will experience menopause earlier than those who have.10 The timing of babies also influences the age at menopause. In studies of Chinese21 and British19 women, those who had their first baby at a younger age and those who had their last baby at an older age, experienced menopause later in life than women with other childbearing patterns. Duration of breastfeeding was also found to influence age at menopause in these women; those who breastfed for longer experienced menopause slightly later than other women.19,21

Age of first menstrual period also influences the age of menopause. Amongst the Chinese women studied, those who began menstruating when they were 16 years or older experienced menopause later than those who began menstruating before they turned 16 years old.21 Women who experienced short menstrual cycles during adolescence also experience menopause, one average, earlier than those who don’t.18


Contraception use
Use of contraceptives (including oral contraceptive, an intrauterine device or tubal ligation) slightly increased the age of menopause amongst Chinese women.21 A study amongst women from the United States also reported that oral contraceptive use was associated with an older age at menopause.23


Other factors
A higher level of education appears to protect against the early onset of menopause,23 as does being married (compared to widowed, single or divorced) and employed (as opposed to unemployed).23 However, it is not clear whether these relationships are direct or are affected by other factors. For example, the relationship between education and menopause timing may occur simply because better educated women are less likely to smoke.10 Being widowed in associated with almost twice the likelihood of early menopause compared to being married, as is poorer general health.10

General lifestyle advice for preventing early menopause

You can’t choose your family and thus can’t influence your genetic risk of early menopause, but you can choose your lifestyle and this will, at least in part, influence the timing of your menopause. Fortunately, many of the things that influence your menopause, also influence your general health.

If you want to keep menopause at bay for as long as possible, quitting smoking, if you haven’t already, is a good place to start. Include moderate portions of meat in your diet and regular rigorous exercise in your daily routine and you’re putting yourself on track to avoid the menopausal alarm blaring a few years earlier than it should.

For women who want to predict the timing of menopause so they can delay childbearing, it’s ironic that the more kids you have (and the earlier you have them after your periods begin) the later in life infertility and menopause set in. It truly is a case of “use it or lose it”! If you don’t want to have a child to extend your reproductive years, thankfully, improving your education or staying employed can also delay menopause, and the preceding infertility, to some degree

But the best evidence for delaying menopause relates to diet, exercise and smoking. Being a non-smoker, healthy eater and regular exerciser are important for general health, not only for extending the fertility period. These measures will not only keep your biological clock ticking and your baby-making goods working that bit longer, they’ll also ensure you’re in optimal health when you decide to get pregnant.

 

Menopause

For more information on menopause, including symptoms and management of menopause, as well as some useful animations and videos, see Menopause.

 

References

  1. MurrayA, Bennett CE, Perry JRB, et al. Common genetic variants are significant risk factors for early menopause: results from the Breakthrough Generations Study. Human Molec Genetics. 2011; 20(1): 186-92. [Abstract | Full text]
  2. Soules MR, Sherman S, Parrott E, et al. Executive summary: Stages of Reproductive Aging Workshop (STRAW). Fertil Steril. 2001; 76(5): 874-8. [Abstract]
  3. Santoro N, Brown JR, Adel T, Skurnick JH. Characterization of reproductive hormonal dynamics in the perimenopause. J Clin Endocrinol Metab. 1996; 81(4): 1495-501. [Abstract]
  4. McKinlay SM, Brambilla DJ, Posner JG. The normal menopause transition. Maturitas. 1992; 14(2): 103-15. [Abstract]
  5. Nelson HD, Haney E, Humphrey L, et al. Management of menopause-related symptoms. Summary, Evidence Report/Technology Assessment No. 120. AHRQ Publication No. 05-E016-1 [online]. Rockville, MD: Agency for Healthcare Research and Quality; March 2005. [cited 14 May 2012]. Available from: URL link
  6. Cobin RH, Futterweit W, Ginzburg SB, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of menopause. Endocr Pract. 2006; 12(3): 315-37. [Full text]
  7. North American Menopause Society. Estrogen and progestogen use in postmenopausal women: 2010 position statement of The North American Menopause Society. Menopause. 2010; 17(2): 242-55. [Abstract]
  8. Fact sheet: Menopause [online]. Clayton, VIC: The Jean Hailes Foundation for Women’s Health; October 2009 [cited 12 July 2010]. Available from: URL link
  9. Burbos N, Morris E. Menopausal symptoms. BMJ Clin Evid. 2010; 2: 804.
  10. Mikkelson TF, Graff-Iversen S. Sundby J. et al. Early menopause association with tobacco smoking, coffee consumption and other lifestyle factors: a cross-sectional study. BMC Public Health. 2007; 7: 149.
  11. Bélisle S, Blake J, Basson R, et al. Canadian consensus conference on menopause, 2006 update. J Obstet Gynaecol Can. 2006; 28(2 Suppl 1): S7-S94. [Abstract | Full text]
  12. Eichling PS, Sahni J. Menopause-related sleep disorders. J Clin Sleep Med. 2005; 1(3): 291-300. [Abstract | Full text]
  13. Accorsi-Neto A, Haidar M, Simoes R, et al. Effects of isoflavones on the skin of postmenopausal women: a pilot study. Clinics. 2009; 64(6): 505-10. [Abstract | Full Text
  14. He C, Kraft P, Chen C, et al. Genome-wide association studies identify novel loci associated with age at menarche and age at natural menopause. Nature Genet. 2009; 41(6): 724-8.
  15. HendersonKD, Bernstein L. Henderson B. et al. Predictors of the Timing of Natural Menopause in the Multiethnic Cohort Study. Am J Epidemiol. 167(11): 1287-94. [Abstract | Full text]
  16. Genetics Home Reference. What are single nucleotide polymorphisms? 2012. [cited 14 May 20121]. Available from: URL Link
  17. Strohsnitter WC, Hatch EE, Hyer M, et al. The Association between In Utero Cigarette Smoke Exposure and Age at Menopause. Am J Epidemiol. 2008. 167(6): 727-33. [Abstract | Full text]
  18. Cramer DW, Barbieri RL, Fraer AR, Harlow BL. Determinants of early follicular phase gonadotrophin and estradiol concentrations in women of late reproductive age. Hum Reprod. 2002; 17(1): 221-7. [Abstract | Full text]
  19. Morris DH, Jones ME, Schoemaker MJ, et al. Body Mass Index, Exercise, and Other Lifestyle Factors in Relation to Age at Natural Menopause: Analyses From the Breakthrough Generations Study. Am J Epidemiol. 2012. Epub ahead of print. [Abstract]
  20. Rehm J, Baliunas D, Borges GLG, et al. The relation between different dimensions of alcohol consumption and burden of disease: an overview. Addiction. 2010; 105: 817-843.  [Abstract]
  21. Dorjgochoo T, Kallianpur A, Gao Y, et al. Dietary and lifestyle predictors of age at natural menopause and reproductive span in the Shanghai Women’s Health Study. Menopause. 2008; 15(5): 924-33. [Abstract | Full text]
  22. Leonetti F, Capoccia D, Coccia F, et al. Obesity, Type 2 Diabetes Mellitus, and Other Comorbidities: A Prospective Cohort Study of Laparoscopic Sleeve Gastrectomy vs Medical Treatment. Arch Surg. 2012. Epub ahead of print. [Abstract | Full text]
  23. Gold EB, Bromberger J, Crawford S, et al. Factors associated with age at natural menopause in a multiethnic sample of midlife women. Am J Epi. 2001; 153: 865-74. [Abstract | Full text]
  24. Canavez FS, Werneck GL, Camara R, et al. The association between education level and age at the menopause: a systematic review. Arch Gynecol Obstet. 2011. 283(1): 83-90. [Abstract | Full text]

Dates

Posted On: 5 June, 2012
Modified On: 15 January, 2014

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