Menstruation is a relatively later feature of puberty and starts at the age of 12 to 14years. It continues more or less regularly throughout childbearing age, and stops usually at the age of 50 to 55 years (menopause).
The menstrual cycle is of 28+or- 2 days. The regularity is generally maintained, but cycle of 21 to 35 days are within normal range. Soon after menarche in some women, the menstrual cycles are irregular for 1-2 years. Similarly, a few years prior to the onset of menopause, menstrual cycle may become irregular.
This means menstrual cycles without any ovulation. This happens at both extremes of fertility periods, soon after menarche and a few years before the onset of menopause.
This result from failure of the follicles in the ovaries to respond to gonadotrophins of the anterior pituitary. The corpus luteum is not formed due to absence of ovulation. Therefore only Graafian follicles are seen in the ovaries, which produce only estrogens. Progesterone is not produced due to the absence of corpus luteum. The menstruation cycle are usually irregular but rarely there may be regular in spite of absence of ovulation. During anovulatory cycle, the endometrium shows only proliferative changes. The secretory changes do not occur because of the absence of progesterone. Due to the anovulatory cycle the fertility rate, soon after menarche and before the onset menopause is low.
Menstruation may last for 2 to 8 days, but the usual duration is 4 to 5 days. The loss of blood during menstruation is usually 40-80 ml. Occasionally it is more than 200ml or only 5ml. This blood does not clot because of the presence of the enzyme fibrinolysis in the endometrium. If the loss is excessive, the enzyme fails to keep the menstrual blood in fluid form then it may clot. This blood is bright red or dark red in color on the first day; it changes to a dark red color and becomes only a brownish vaginal discharge during the last days of menstruation. The cycle is described as a fraction of flow/length of the cycle. E.g. 5/28 or 4/28.
Most of the women experience some degree of discomfort associated with menstruation. In a majority of them the discomfort is mild. It is associated with menstruation may be general or local.
General: These symptoms usually occur before the onset of menstruation. For 2 to 3 days, she may feel giddy, complain of headache, and feel tired, irritated or depressed. She may complain of general malaise or dyspepsia and may get tingling sensation in her breast. The women usually complain of weight gain during premenstrual period. This is primarily due to estrogens and aldosterone.
Local: A majority of women get only lower abdominal discomfort or backache. On the first day of menstruation, especially in nulliparous women, the backache may get worse, and there may be associated with lower abdominal colicky pain (abdominal cramps). She may also have a feeling of heaviness in the lower abdomen and frequency of micturition.