Risk factors in ectopic pregnancy. Results of a population-based case-control study.

In a population-based case-control study, possible risk factors for ectopic pregnancy were compared in 119 patients with ectopic pregnancy and in 119 age-matched controls with intra-uterine pregnancy from each of the following categories: deliveries, spontaneous abortions and induced abortions. The following factors were found significantly more often in cases of ectopic pregnancy: a history of earlier ectopic pregnancy, a history of salpingitis, a history of earlier operation on the Fallopian tubes, a history of infertility, and a pregnancy that had occurred in spite of an intra-uterine contraceptive device. A history of appendectomy was also found significantly more often among the cases. There was no significant correlation between ectopic pregnancy and a history of no earlier pregnancy, earlier deliveries, earlier spontaneous or induced abortions or a history of other gynecological operations and increased risk of ectopic pregnancy. One or more of the risk factors were found in 76.5% of cases and 23% of controls.