About the Menstrual Cycle
The menstrual cycle lasts an average of 28 days, during which time the body releases a series of hormones in preparation for pregnancy. In the early stages of the menstrual cycle, the hypothalamus releases follicle-stimulating hormone releasing factor (FSH-RF), which stimulates to pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH both stimulate the follicles of the ovaries, which contain the eggs, to mature and prepare an egg for release. At this point, the ovaries release estrogen, and continue to do so for seven days until the egg is mature enough for fertilization. When estrogen levels are high enough, the hypothalamus releases a final burst of FSH-RF and stimulates the pituitary to release a large surge of FSH. The final surge of FSH causes the follicle to open and release the egg, initiating ovulation. During ovulation, the body releases progesterone, which causes the lining of the uterus to thicken. If the egg is fertilized, it implants in the uterus and develops into a fetus. If the egg is not fertilized, the lining of the uterus sloughs off and menstruation begins.
Other Effects of Menstrual Hormones
Estrogen and progesterone are both primarily responsible for preparing the reproductive system for pregnancy. These hormones also have other effects on the body, which account for many of the symptoms that women experience during the menstrual cycle. According to the American College of Obstetricians and Gynecologists, as much as 80 percent of women experience physical changes during the menstrual cycle. In some women, these effects--cramping, bloating and breast tenderness among them--may be bothersome but manageable. Many women also experience minor changes in mood and may become irritable, have a higher sex drive and even experience euphoria. Some women, however, may experienced premenstrual syndrome (PMS) characterized by more intense physical discomfort and depression. In severe cases, women may experience a more debilitating form of PMS known as premenstrual dysmorphic disorder (PMDD). According to ACOG, 20 percent to 40 percent of women experience symptoms of PMS and another 2 to 10 percent report severe symptoms, which disrupt their daily activities.
Menstrual Hormones and Depression
According to the Mayo Clinic, twice as many women as men experience depression. Scientists are not entirely clear how premenstrual hormonal changes affect depression. One theory is that, in some women, estrogen and other hormones may interfere with serotonin (a neurotransmitter that controls mood). Because not all women experience depression with their menstrual cycles, scientists also believe some women may be genetically predisposed. There is also the possibility that some women may produce too many hormones, or be overly sensitive to their effects. Diet and health status may also influence hormone production and contribute to premenstrual and menstrual depression.