Menopause is a natural stage of life and most women are aware that they’ll experience it at some point. But there’s one phase linked to menopause that doesn’t get as much attention: perimenopause.

Perimenopause marks one of the early stages of menopause where you might notice some changes in your body. But what is perimenopause, exactly, and how can you know if you’re experiencing it? These are the perimenopause symptoms you need to know about.

What is perimenopause?

Perimenopause is a term used to describe the years leading up to menopause. The amount of estrogen produced by the ovaries begins to fluctuate in your 30s and 40s, and this can lead to a range of perimenopausal symptoms.

Women start perimenopause at different ages: Some can notice changes as early as their mid-30s, while others may notice signs of perimenopause in their 40s.

Once you’ve been through 12 consecutive months without a period, you’ve officially reached menopause, signalling the end of perimenopause, says obstetrician and gynaecologist  Dr Christine Greves. (Menopause usually starts between ages 45 and 55.)

What are the symptoms of perimenopause?

The symptoms of perimenopause can vary, but women will typically experience one or several of the following:

Irregular periods

The change in oestrogen production can interfere with your period, says Dr Lauren Streicher, an obstetrician, gynaecologist and author of Hot Flash Hell. “Your periods may become longer or shorter,” she says, adding that you might also start to skip periods. Even your flow can be impacted—it can be lighter or heavier.

Hot flushes

A hot flush is a sudden feeling of warmth that rushes to your upper body and face. It can last anywhere from a few seconds to a few minutes and can happen as often as several times a day. Just like with “regular” menopause, you can experience hot flushes with perimenopause. “It’s due to the oestrogen deficiency,” Dr Greves explains.

Mood changes

There are a few reasons why women may have mood changes during perimenopause. It’s common to have sleep problems during perimenopause and that can impact a woman’s mood, Dr Streicher says. “Sometimes women may not be happy with the changes that are going on in their bodies and that can impact mood, too,” Dr Greves says, noting that hot flushes don’t help.

Vaginal dryness

As oestrogen levels in the body decrease, the lining of the vagina may become thinner, dryer, and less elastic. “Oestrogen is like lotion to your vagina,” Dr Greves says. “Without it, there can be vaginal dryness.”

A change in sex drive

Vaginal dryness can cause pain or discomfort during sex and that alone can decrease a woman’s sex drive, Dr Streicher says. But levels of the hormone testosterone in your body decrease during perimenopause, and that can also impact sex drive, Dr Greves says. (P.S. Here are some tips on how to increase your libido).

A decrease in fertility

Because ovulation is irregular during perimenopause, your ability to get pregnant drops, the Mayo Clinic says. However, it’s still possible to get pregnant, warns Dr Mary Jane Minkin, an obstetrics and gynaecology specialist “Until you go a full year without a period, you cannot tell someone she will not get pregnant,” Dr Minkin says. “I personally have delivered three babies to 47-year-old ladies who were not trying to get pregnant.” If you don’t want to become pregnant and you suspect you’re in perimenopause, Dr Streicher recommends using birth control until you haven’t had a period for 12 months.

Loss of bone

It’s unlikely you’ll notice this, but you start to lose more bone than you replace during perimenopause because of declining oestrogen levels. This increases your risk of osteoporosis, a disease that leads to fragile bones.

Increase in bad cholesterol

Another symptom you’re unlikely to notice: Lowering oestrogen levels could lead to an increase in low-density lipoprotein (LDL) cholesterol (aka “bad” cholesterol) and a decrease in high-density lipoprotein (HDL) cholesterol (aka “good cholesterol”). Together, these can raise your risk of developing heart disease.

What to do about perimenopausal symptoms

If you have perimenopausal symptoms and they’re not bothering you, there’s no need to take any medication or undergo treatment, Dr Greves says. But, if you’re dealing with symptoms like hot flushes and unpredictable bleeding, Dr Minkin points out that low-dose birth control pills, which deliver progesterone and oestrogen, can help. (An added bonus, if you’re not trying to conceive: They can help lower your risk of pregnancy.)

Dr Streicher agrees that birth control pills can help. “A lot of women think that the doctor is brushing them off by suggesting they go on a birth control pill when, in fact, it can be an effective way to mitigate these symptoms,” she says.

If you think you're in perimenopause, talk to your doctor about your options. They should be able to help provide guidance.