Oligomenorrhea: This is defined as infrequent or light menstruation experienced by a menstruating woman who previously had periods that were normal.

This condition normally happens in women with PCOS or polycystic ovarian syndrome. It may also be caused by physical or emotional stress, tumors secreting estrogen, chronic illness, poor nutrition as well as eating disorders such as anorexia nevosa. Serious female athletes often develop this condition due to a strict diet as well as intense physical training which leads to a very low percentage of body fat.

This condition can also be due to hormonal imbalance. The beginning of menstruation in puberty and the regularity and length of the menstrual cycle is well-ordered by hormones created in a part of the brain known as the hypothalamus, as well as by the adrenal and pituitary glands. It is quite common as well as normal for the hormone messages sent to these glands to get out of sync in girls who have just begun menstruating. It should also be noted that there are a few women who menstruate on a schedule that is regularly infrequently as once every 2 months, for no apparent reason. For them the irregular schedule is normal and not any reason for concern.