Prevalence and risk factors of severe obstetric haemorrhage.

OBJECTIVE: To determine the prevalence, causes, risk factors and acute maternal complications of severe obstetric haemorrhage.
DESIGN: Population-based registry study. POPULATION: All women giving birth (307,415) from 1 January 1999 to 30 April 2004 registered in the Medical Birth Registry of Norway. Information about socio-economic risk factors was obtained from Statistics Norway.
METHODS: Cross-tabulation was used to study prevalence, causes and acute maternal complications of severe obstetric haemorrhage. Associations of severe obstetric haemorrhage with demographic, medical and obstetric risk factors were estimated using multiple logistic regression models. MAIN OUTCOME MEASURE: Severe obstetric haemorrhage (blood loss of > 1500 ml or blood transfusion).
RESULTS: Severe obstetric haemorrhage was identified in 3501 women (1.1%). Uterine atony, retained placenta and trauma were identified causes in 30, 18 and 13.9% of women, respectively. The demographic factors of a maternal age of > or =30 years and South-East Asian ethnicity were significantly associated with an increased risk of haemorrhage. The risk was lower in women of Middle Eastern ethnicity, more than three and two times higher for emergency caesarean delivery and elective caesarean than for vaginal birth, respectively, and substantially higher for multiple pregnancies, von Willebrand's disease and anaemia (haemoglobin <9 g/dl) during pregnancy. Admissions to an intensive care unit, postpartum sepsis, hysterectomy, acute renal failure and maternal deaths were significantly more common among women with severe haemorrhage.
CONCLUSION: The high prevalence of severe obstetric haemorrhage indicates the need to review labour management procedures. Demographic and medical risk factors can be managed with extra vigilance.