Risk factors of ectopic pregnancy

OBJECTIVES: To assess the risk factors of ectopic pregnancy in Thai women. SETTING: Department of Obstetrics and Gynaecology, Faculty of Medicine, Chulalongkorn University. DESIGN: Case controlled study. MATERIAL AND METHOD: From 1999 to 2000, 208 cases of ectopic pregnancy and 781 controls (postpartum women) were included in the study. The women were interviewed by trained research interviewers using a standardized questionnaire. Detailed information regarding age at first intercourse, number of sexual partners, history of changing partners within 6 months, previous obstetric history, history of spontaneous and criminal abortion, history of pelvic inflammatory disease, smoking, history of endometriosis and history of previous ectopic pregnancy was collected. RESULTS: By multivariate analysis, 5 variables remained as strong and independent risk factors for ectopic pregnancy: the number of sexual partners > or = 2 (OR = 3.02, 95% CI (1.75-5.23), vaginal delivery > or = 1 (OR = 0.005, 95% CI (0.002-0.0015), history of pelvic inflamatory disease (OR = 3.17, 95% CI (1.40-7.19), smoking (OR = 2.49, 95% CI (1.36-4.55), infertility (OR = 2.74, 95% CI (1.35-5.54)). CONCLUSION: Problems of multiple sexual partners, pelvic inflammatory disease, smoking and infertility were the main risk factors of ectopic pregnancy in Thai women.