Placenta praevia is a form of impaired placentation in which placenta lies in the lower segment of the uterine cavity, covering partially or completely the internal cervical ostium, preventing normal vaginal delivery. A trend of increasing placenta praevia incidence was observed in the past decade, the studies show it is mainly due to an increasing caesarian section rate and advancing maternal age at time of first pregnancy (Iyasu et al., 1993). The etiology of placenta praevia is not known, but an association has been found between previous history of caesarian section, high parity and advanced maternal age. Other potential risk factors include previous abortions, previous placenta praevia, previous gynaecological problems, procedures like dilatation and curettage, use of intrauterine contraceptive devices, infertility treatment, etc. The results of the studies of the risk factors of placenta praevia vary around the world and are sometimes contradictory.