The years before you finally hit menopause are called perimenopause, and consist of the changes we associate with ‘menopausal symptoms’ – hot flashes, night sweats, dry vagina, infrequent periods. Perimenopause appears two or three years before ovulation actually grinds to a halt, with first progesterone declining, and then oestrogen dropping off. Your ovulation and periods may become less frequent, or stop and start unpredictably.

Oddly timed ovulations is how some women end up pregnant in their late forties or fifties! They think they’ve been cut loose from it all, only to find themselves having a final hurrah ovulation that has resulted in a pregnancy. While this is not that common, it does happen.

There are two ways to enter menopause – either through surgical or medical interventions (removal of ovaries) or naturally, with age. What age you hit menopause will vary, with the best indicator being genetic – ask around your mother and any of her siblings. The slower perimenopause is, the fewer symptoms are experienced, but it’s very difficult to predict what will happen to you.

The hormones that cause menopausal symptoms

Oestrogen normally inhibits follicle-stimulating hormone (FSH), but as oestrogen decreases, blood levels of FSH become clear on a blood test – this is one of the indicator tests for menopause. FSH and luteinising hormone (LH) are released about every 60-90 minutes in small bursts, with the burst of LH understood to coincide with hot flashes.

LH also stimulates the ovaries to produce an androgen that is converted into a form of oestrogen (oestrone), which is the most dominant type of oestrogen in postmenopausal women. Oestrone production in postmenopausal women tends to have very little to do with the ovary, however, and is mostly the job of the adrenal glands, as they produce the majority of the androgen that is converted to oestrone, then mostly the fat cells turning it into oestrone. This means the more fat you carry, the more oestrone you will have in menopause, which correlates with greater bone density and fewer menopausal symptoms.

Oestrone is about 12 times weaker than your usual oestrogen from the ovaries, oestradiol. The oestrogen effect in menopause is heavily reduced. Without as much oestrogen, androgens behave differently too, but only drops by about 15 per cent. This means that overall, androgens are more dominant. The ‘androgen body type’ is that of a man’s, with skinny legs and a bigger midsection. This loss of androgens is also believed to contribute to menopausal symptoms, because half our testosterone is produced by the ovaries, with 10 per cent from adrenals, and the rest converted in our fat cells.

The testosterone levels of a woman in her forties are half that of a woman in her twenties. Low levels of testosterone are thought to contribute to low mood, less stamina, lowered libido, and other symptoms. Conversely, some women will see male-pattern hair loss or facial hair growth, caused by the effect of DHEA on hair follicles.

Progesterone is produced unpredictably in perimenopause. Progesterone is produced by ovulation, so the less ovulation that occurs, the less progesterone being produced. Progesterone declining can cause mood changes and heavier periods.

All these changes together cause the physical and chemical changes that characterise menopause, bringing with them hot flushes, mood changes, and menstrual cycle changes.

Signs and symptoms of perimenopause

First phase – changes in progesterone and oestrogen levels

  • Periods become less frequent
  • Cycle length increases
  • Vaginal dryness
  • Insomnia
  • Hot flushes
  • Night sweats

Second phase – menopause arrives

  • Periods may stop completely suddenly
  • Very sparse periods
  • ‘Flooding’ period, usually right before they stop altogether

Tests for menopause

The FSH test is not always very accurate, since your FSH levels can fluctuate during the day or day to day during perimenopause. This can be misleading. Once you have become menopausal, however, FSH levels will stay high, but you won’t need a test to tell you that – you will know.

The best time to take the FSH test is three days after your period starts – if your result is >10 IU/L, it indicates a perimenopausal state. Oestradiol levels should also be taken at the same time, with a reading of <150 pmol/l suggestive of perimenopause.

If you have had a hysterectomy and there is doubt regarding your test due to no periods, FSH alone may be useful in determining what is going on. Progesterone and oestrogen tests are even less reliable, and is typically a waste of time and money. If you are on oral hormone replacement therapy, results will be inaccurate.

The look of your vaginal walls is a good indicator of where you’re at, with thinner, drier, easily-disturbed tissue a good indicator of lowered oestrogen levels.

How can I tell if I am menopausal?

If you haven’t had a period for a year, and there is nothing else to suggest something is wrong (you are too young, there is unusual bleeding or other symptoms), then you can suppose that menopause has arrived.