What else can cause irregular periods?
The commonest cause of infrequent periods is a condition called polycystic ovaries (PCOS). Women with PCOS have a large number of very small (less than 1cm) cysts on their ovaries and a hormone imbalance. The cysts interfere with regular ovulation and so periods are infrequent. PCOS is a common condition that affects as many as 10 per cent of women.
