Severe Obstetric haemorrhage is the main cause of severe maternal morbidity and mortality world wide. In this thesis, data from the Medical Birth registry of Norway was analaysed to determine the proportion, risk factors, causes and maternal and perinatal outcome of severe obstetric haemorrhage among 307 415 mothers in 1999-2004 as well as of uterine rupture in 18 794 mothers after previous caesarean section (CS) in 1999-2006. Severe obstetric haemorrhage occcured in 1.1% of all mothers, and was significantly associated with serious maternal outcome, such as death and hysterectomy. Emergency CS. followed by elective CS were most important risk factors. Other risk factors were multiple pregnancy, HELLP syndrome, anaemia, macrosomia, induction of labour, and older maternal age.Uterine rupture occured in 5/1000 of mothers with previous CS. The highest risk was for induced labour, especially with prostaglandins, while lowest risk was for elective CS. Severe obstetric haemorrhage was to a major extent related to obstetric procedures and labour management, indicating that induction and prelabour CS should be practiced with caution.