During each of the major reproductive phases of a woman’s life described above, various hormonal glands in her body work together to control how much of each hormone is produced. Glands including the pituitary, ovaries and thyroid all play a role in the transition into menopause. Even other organs/tissue such as the uterus, breast tissue and fat cells (adipose tissue) are capable of secreting hormones that influence reproduction.

The major hormonal changes involved in perimenopause, menopause and postmenopause include estrogen, progesterone and testosterone. While other hormones are also usually shifting and involved (including serotonin and insulin), these three have the biggest influence over a woman’s reproductive capabilities - especially estrogen.

Estrogen is the collective term for three types of female hormones (estoril, estradiol and estrone) that are mostly secreted by the ovaries. The three types of estrogen are primarily responsible for giving a woman her female qualities (and to some degree men too), including her reproductive capabilities, fat around her hips/thighs and her smooth skin.

Progesterone is the hormone that prepares the uterus for pregnancy in addition to having other jobs, and testosterone is the hormone mostly associated with masculine qualities.

When your ovaries stop making a high percentage of your body’s estrogen (they’re responsible for 90 percent of production prior to menopause), you enter menopause. Because estrogen has important effects on your bodyweight and composition, mood, sleep, sex drive, cognitive function, memory, and blood flow, many different symptoms can be experienced during perimenopause/menopause as a result of decreasing estrogen levels.

Can you still become pregnant during perimenopause, you might be asking yourself? Technically, yes you can. Although the menstrual cycle is irregular and fertility at this time in a woman’s life is low, it’s not impossible to become pregnant until entering menopause.