Menopause is the absence of menstrual periods for 12 months. The menopausal transition starts with varying menstrual cycle length and ends with the final menstrual period. Perimenopause means “the time around menopause” and is often used to refer to the menopausal transitional period. It is not officially a medical term, but is sometimes used to explain certain aspects of the menopause transition in lay terms. Postmenopause is the entire period of time that comes after the last menstrual period.
Menopause is the time in a woman’s life when the function of the ovaries ceases. The ovary, or female gonad, is one of a pair of reproductive glands in women. They are located in the pelvis, one on each side of the uterus. Each ovary is about the size and shape of an almond. The ovaries produce eggs (ova) and female hormones such as estrogen. During each monthly menstrual cycle, an egg is released from one ovary. The egg travels from the ovary through a Fallopian tube to the uterus.
The ovaries are the main source of female hormones, which control the development of female body characteristics such as the breasts, body shape, and body hair. The hormones also regulate the menstrual cycle and pregnancy. Estrogens also protect the bone. Therefore, a woman can develop osteoporosis (thinning of bone) later in life when her ovaries do not produce adequate estrogen.
Perimenopause is different for each woman. Scientists are still trying to identify all the factors that initiate and influence this transition period.
Signs and Symptoms
- Irregular periods that can be heavy, light, shorter, or longer
- Occasional hot flashes and/or night sweats
- Unpredictable mood swings, depression, anxiety, or irritability
- Difficulty getting to sleep or staying asleep
- Memory loss
- Variations in breast tenderness or fullness
- Loss of or decreased sexual desire
- Vaginal dryness
- Alterations in body fat composition
- Heart palpitations
- Decreased bone density
- Dry skin
- Hair loss
Menopause occurs when a woman’s ovaries run out of functioning eggs. At the time of birth, most females have about 1-3 million eggs, which are gradually lost throughout a woman’s life. By the time of a girl’s first menstrual period, she has an average of about 400,000 eggs. By the time of menopause, a woman may have fewer than 10,000 eggs. A small percentage of these eggs are lost through normal ovulation (the monthly cycle). Most eggs die off through a process called atresia.
Normally, FSH, or follicle-stimulating hormone (a reproductive hormone), is the substance responsible for the growth of ovarian follicles (eggs) during the first half of a woman’s menstrual cycle. As menopause approaches, the remaining eggs become more resistant to FSH, and the ovaries dramatically reduce their production of a hormone called estrogen.
Estrogen affects many parts of the body, including the blood vessels, heart, bone, breasts, uterus, urinary system, skin, and brain. Loss of estrogen is believed to be the cause of many of the symptoms associated with menopause. At the time of menopause, the ovaries also decrease their production of testosterone—a hormone involved in the libido, or sexual drive.