Post partum haemorrhage is abnormal vaginal bleeding after delivery. It is described as primary or secondary. Primary post partum haemorrhage is defined as the loss of more than 500 mls of blood in the first 24 hours, while secondary postpartum haemorrhage occurs later - usually between five and 12 days. Primary haemorrhage is most often due to genital tract trauma during delivery, or uterine abnormality such as fibroids, though women with clotting disorders are also at risk. Secondary haemorrhage is usually due to the presence of retained products of conception - either placenta or membranes - or uterine infection. Very rarely it may be due to the development of chorionic carcinoma. After delivery the uterus contracts and becomes smaller, a process called involution. This is usually monitored by the midwife. Failure of involution may be due to the presence of retained products of conception, and merit investigation