Main Risk Factors for Ectopic Pregnancy: A Case-Control Study in A Sample of Iranian Women

BACKGROUND: Although the risk factors of ectopic pregnancy have been determined in previous studies, the main risk factors of ectopic pregnancy are different in various countries due to different cultural and social characteristics. Determination of main risk factors of ectopic pregnancy leads to a rapid diagnosis and an improvement in strategies for its prevention. The purpose of this study was to determine the main risk factors of ectopic pregnancy in a sample of Iranian women. MATERIALS AND METHODS: We designed a case-control study to include 150 cases and 300 controls and to compare them by the following factors: socio-demographic characteristics, contraceptive methods, prior tubal surgery, tubal pathology, prior ectopic pregnancy, prior caesarean section, prior abortion, prior infertility, and prior abdominal/pelvic surgery. RESULTS: The case and control groups were significantly similar in term of education and parity. There was an association between ectopic pregnancy and age which was disappeared after controlling for the main risk factors (adjusted OR=2.45, 95% CI: 0.86-6.97). There was no statistically significant relation between ectopic pregnancy and prior tubal surgery, tubal pathology, prior abortion, prior infertility, assisted reproductive technology, and oral contraceptive method (p>0.05). However, there was a significant association between prior ectopic pregnancy, prior tubal ligation, use of intrauterine device, and prior abdominal/pelvic surgery with ectopic pregnancy (p<0.05). The risk of ectopic pregnancy increased with the use of intrauterine device and tubal ligation, whereas decreased with use of oral contraception. CONCLUSION: This study identified prior ectopic pregnancy, prior tubal ligation, use of intrauterine device, and prior pelvic/abdominal surgery as the main risk factors for ectopic pregnancy in a sample of Iranian women. Our findings can be useful for early diagnosis of ectopic pregnancy and for improvement in strategies of its prevention through medical therapy instead of unnecessarily surgical treatment.