Introduction: Ectopic pregnancy is a public health problem and their risk factors are unknown. This study was performed to identify risk factors for better diagnosis and treatment of this disease.

Methods: A case-control study on 195 cases of ectopic pregnancy (Case group) and 197 normal pregnancies (control group) were performed in Shahid Sadoughi and mother hospitals in Yazd city as representatives of public and private sectors. Cases of control group were pregnant women who entered immediately before and after the cases for delivery (normal or cesarean).

Results: The mean age was 28.2±5.6, ranged from 14 to 45, and marriage age varied from 12 to 33 years. There was no significant difference between cases and controls according to body mass index (P=0.72). Inunivariate analysis, history of infertility (OR: 3.18, 95% CI= 1.9-5.2,

 P= 0.001), history of infections (OR: 1.67,  95%  CI= 1.10-2.53,  P= 0.01), use of intrauterine device (IUD) (OR:2.78,  95% CI= 1.08-7.16,  P= 0.03) and tobacco smoking (OR: 2.96,  95%  CI= 1.21-7.21,  P= 0.01) were determined as risk factors for ectopic pregnancy.

Conclusion: This study demonstrates that history of infertility; use of IUD and oral contraceptive use are associated with ectopic pregnancy.