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.
Natural Cycles
The most recent published clinical study showed that natural cycles, when used correctly, is as effective in preventing pregnancies as the contraceptive pill.
The study analysed 22,785 women through a total of 224,563 menstrual cycles across a year, to calculate the app’s Pearl Index – the rate used to measure a contraceptive effectiveness. It found that if used perfectly – using protection such as condoms on red days – effectiveness is 99 percent. Typical use, where people become pregnant for all possible reasons, leads to 93 percent effectiveness. This is well above other Fertility awareness based methods that rate at around 75 percent and even the contraceptive pill, which rates at 91 percent. Further studies include the “Identification and prediction of the fertile window using Natural Cycles" and “Fertility awareness-based mobile application for contraception”. For the app to remain effective, women need to follow the app's instructions correctly, and it does not protect its users from sexually transmitted diseases.