Menstruation
Menstruation, also known as a period or monthly, is the regular discharge of blood and mucosal tissue (known as menses) from the inner lining of the uterus through the vagina. The first period usually begins between twelve and fifteen years of age, a point in time known as menarche. However, periods may occasionally start as young as eight years old and still be considered normal. The average age of the first period is generally later in the developing world, and earlier in the developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days). Bleeding usually lasts around 2 to 7 days. Menstruation stops occurring after menopause, which usually occurs between 45 and 55 years of age. Periods also stop during pregnancy and typically do not resume during the initial months of breastfeeding.
Up to 80% of women report having some symptoms prior to menstruation. Common signs and symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mood changes. These may interfere with normal life, therefore qualifying as premenstrual syndrome, in 20 to 30% of women. In 3 to 8%, symptoms are severe.
A lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not occurred in 90 days. Other problems with the menstrual cycle include painful periods and abnormal bleeding such as bleeding between periods or heavy bleeding. Menstruation in other animals occur in primates (apes and monkeys).
The menstrual cycle occurs due to the rise and fall of hormones. This cycle results in the thickening of the lining of the uterus, and the growth of an egg, (which is required for pregnancy). The egg is released from an ovary around day fourteen in the cycle; the thickened lining of the uterus provides nutrients to an embryo after implantation. If pregnancy does not occur, the lining is released in what is known as menstruation.
Menstrual cycle
The different phases of the menstrual cycle correlate with women's moods. In some cases, hormones released during the menstrual cycle can cause behavioral changes in females; mild to severe mood changes can occur. The menstrual cycle phase and ovarian hormones may contribute to increased empathy in women. The natural shift of hormone levels during the different phases of the menstrual cycle has been studied in conjunction with test scores. When completing empathy exercises, women in the follicular stage of their menstrual cycle performed better than women in their midluteal phase. A significant correlation between progesterone levels and the ability to accurately recognize emotion was found. Performances on emotion recognition tasks were better when women had lower progesterone levels. Women in the follicular stage showed higher emotion recognition accuracy than their midluteal phase counterparts. Women were found to react more to negative stimuli when in midluteal stage over the women in the follicular stage, perhaps indicating more reactivity to social stress during that menstrual cycle phase. Overall, it has been found that women in the follicular phase demonstrated better performance in tasks that contain empathetic traits.