What role do hormones play?

Hormonal changes guide all reproductive processes from adolescence to menopause, including menstruation, ovulation, pregnancy, childbirth, and breastfeeding. In addition to these reproductive actions, hormones also affect mood, libido, alertness, and bone density.

During adolescence, female reproductive hormones stimulate breast growth, feminine fat distribution, broadening of the hips, uterus enlargement, development of the external genitalia, hair distribution, and skin softness. After adolescence, hormones drive the reproductive processes of ovulation, menstruation, and pregnancy.

Girls typically begin to menstruate between ages 11 and 14. With its falling and rising hormone levels, this menstrual cycle dictates the days in which a woman may become pregnant. Menstrual bleeding occurs at the beginning of each cycle to remove the old endometrial layer from the uterus.

If the egg becomes fertilized during ovulation, hormones secreted by the placenta prevent menstruation, and pregnancy results. As the baby grows, estrogen and progesterone levels continue to rise, until they reach a peak at birth. Further interaction between hormones leads to contractions of the uterus, which results in childbirth. After the baby is born, other hormones make nursing possible.

Women continue the menstrual cycle until about 51 years of age, when they experience menopause, or ovarian failure. As reproductive hormone levels drop off, women experience drastic bodily changes, like vaginal dryness, decrease in libido, and loss of bone density.

But their effects are not only physical – hormones also influence mood, libido, appearance, self-image, and comfort. For example, during ovulation, many women experience heightened sexual desire. And almost all women are familiar with the mood swings and insecurity that accompany premenstrual syndrome.