Haemorrhage is a major cause of maternal mortality. In developing countries it causes about 28% (> 125 000) of known maternal deaths each year; the risk is approximately one in 1000 deliveries. In developed countries, antenatal ultrasonic diagnosis of placenta praevia, routine use of oxytocics in the third stage of labour, blood transfusion and intensive care have greatly reduced maternal deaths due to haemorrhage. In the UK, the maternal mortality rate is less than one in 100 000. Haemorrhage is a leading cause of these deaths. Twenty-two maternal deaths, 17 directly due to haemorrhage, and five in which haemorrhage played a significant part, were reported to the CEMD in the triennium 2000–2002. Severe, possibly life-threatening, haemorrhage occurs in approximately 6.7 per 1000 deliveries in the UK. Haemorrhage may also cause significant morbidity in survivors by predisposing to anaemia and infection.

Definition

Massive obstetric haemorrhage implies the loss of large, potentially life-threatening, amounts of blood from the genital tract. Various definitions have been suggested: blood loss in excess of 1000 or 1500 ml from the genital tract, blood loss of more than 150 ml per minute, blood loss requiring immediate transfusion or transfusion of more than ten units of blood within 24 hours, or replacement of the patient's total blood volume or 50% of the circulating blood volume in less than three hours. In practice, accurate measurement of blood loss is difficult and the amount and rate of bleeding is often underestimated.