Oligo-ovulation (irregular ovulation)

Oligo-ovulation, also called irregular ovulation, describes ovulation that happens infrequently or unpredictably rather than not at all. It usually presents as irregular or widely spaced periods and reduces the number of fertile cycles in a year. Like full anovulation, it is commonly linked to PCOS, thyroid dysfunction or raised prolactin, and is generally assessed and treated in the same way, with ovulation tracking and, if needed, ovulation induction.

Also known as: irregular ovulation, infrequent ovulation, oligomenorrhoea

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.