The objective of the study was to determine which background factors predispose women to primary postpartum haemorrhage (PPH) at the Obafemi Awolowo University Hospital. The study consisted of 101 women who developed PPH after a normal vaginal delivery and 107 women with normal unassisted vaginal delivery without PPH Both cases and controls were investigated for sociodemographic risk factors, medical and obstetric histories, antenatal events and labour and delivery outcomes. Data were abstracted from the medical and delivery records and risks were estimated by multivariate logistic regression. The results of the univariate analysis revealed a number of potential risk factors for PPH but after adjustment by logistic regression three factors remained significant. These were prolonged second and third stages of labour and non-use of oxytocics after vaginal delivery. Previously hypothesised risk factors for PPH such as grand multiparity, primigravidity and previous episodes of PPH were not significantly associated with PPH. We conclude that primary PPH in this population is mostly associated with prolonged second and third stages of labour and non use of oxytocics. Efforts to reduce the incidence of PPH should not only be directed at proper management of labour but also training and retraining of primary health care workers and alternative health care providers in the early referral of patients with prolonged labour.