Cycle and ovulation
Oligomenorrhoea describes periods arriving less often than every 35 days or fewer than about nine times a year. It is one of the diagnostic features considered in PCOS and typically reflects infrequent ovulation, so it is investigated with hormone tests and an ovarian ultrasound.
Also known as: oligomenorrhea, infrequent periods
Sources
- Royal Australian and New Zealand College of Obstetricians and Gynaecologists (ranzcog.edu.au)
Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.