Oligomenorrhea is an abnormal bleeding pattern where menstrual bleeding occurs at intervals of greater than 35 days, with fewer than 9 periods in a year. The period may be light in flow, short in duration or occur at irregular intervals. Oligomenorrhea is common in adolescent females in the first few years following menarche.

Causes of oligomenorrhea range from chromosomal abnormalities to hypothalamic-pituitary conditions to hormonal imbalances. A common cause of oligomenorrhea is polycystic ovary syndrome