Menarche is the name given to the time when an adolescent girl has her first period. Before the first period arrives, most girls will have shown the physical signs of puberty, such as breast development and fine hair growth in the pubic region. The preparation for menstruation begins when the ovaries produce two hormones, estrogen and progesterone, that trigger certain changes in the female’s reproductive system. Prior to the onset of menstruation, many girls notice some wetness, as an increase in vaginal discharge occurs. Typically, menstruation occurs at the end of puberty, on average about eighteen months after the peak of the growth spurt. Menstruation, the monthly flow of blood from the uterus, is a signal that a female is physically mature and capable of becoming pregnant. The average age in the India for the onset of menstruation is between 10 and 16 years.
The menstrual cycle typically lasts from the first day of one period to the first day of the next period. The typical cycle of an adult female lasts approximately 28 days, although some females experience cycles as short as 22 days, while others are as long as 35 days. For the first few years after menarche, menstrual periods are often irregular. The menstrual cycle can be very irregular for the first one or two years, usually being longer than the average of 28 days. For example, they may be shorter (3 weeks) or longer (6 weeks), or the female adolescent may only have three or four periods a year.