BackgroundPost caesarean wound infection is not only a leading cause of prolonged hospital stay but a major cause of the widespread aversion to caesarean delivery in developing countries. In order to control and prevent post caesarean wound infection in our environment there is the need to access the relative contribution of each aetiologic factor. Though some studies in our environment have identified factors associated with post caesarean wound infection, none was specifically designed to address these issues prospectively or assess the relative contribution of each of the risk factors.FindingsProspective multicentre study over a period of 56 months in Lagos Nigeria. All consecutive and consenting women scheduled for caesarean section and meeting the inclusion criteria were enrolled into the study. Cases were all subjects with post caesarean wound infection. Those without wound infection served as controls. Data entry and analysis were performed using EPI-Info programme version 6 and SPSS for windows version 10.0.Eight hundred and seventeen women were enrolled into the study. Seventy six (9.3%) of these cases were complicated with wound infection. The proportion of subjects with body mass index greater than 25 was significantly higher among the subjects with wound infection (51.3%) than in the subjects without wound infection (33.9%) p = 0.011. There were also significantly higher proportions of subjects with prolonged rupture of membrane (p = 0.02), prolonged operation time (p = 0.001), anaemia (p = 0.031) and multiple vaginal examinations during labour (0.021) among the women that had wound infection compared to the women that did not have wound infection. After adjustment for confounders only prolonged rupture of membrane (OR = 4.45), prolonged operation time (OR = 2.87) and body max index > 25 (2.34) retained their association with post caesarean wound infection.ConclusionEffort should be geared towards the prevention of prolonged rupture of fetal membrane and the reduction of prolonged operation time by the use of potent antibiotics, early intervention and use of good surgical technique. In obese women improved surgical technique and use of non absorbable sutures may suffice.