A common cause of irregular periods is polycystic ovarian syndrome, or PCOS. This is caused by a hormone imbalance that disrupts ovulation. Instead of one egg maturing and being released each cycle, the immature eggs are trapped in their follicles, which are seen as little bumps on the surface of the ovary.
Although women with PCOS may have a high Body Mass Index (BMI) not all with this condition are overweight.
Symptoms may include: irregular menstrual periods, excessive hair growth, acne and weight gain.
Diagnosis: scan of ovaries, hormone testing.
Possible solutions: changes to diet and lifestyle can help boost natural fertility. A weight loss of just five per cent can re-start regular ovulation in obese women.
Ovulation stimulating drugs such as clomiphene and gonadotrophins may be prescribed to boost ovulation, followed by timed natural intercourse, but careful monitoring is needed as women with PCOS can have their ovaries over-stimulated.
If these measures are unsuccessful then IVF with fertility drugs is recommended.