Smoking and reproductive health: cigarette smoking as a risk factor in ectopic pregnancy.

To evaluate the association between ectopic pregnancy (EP) and smoking, a hospital based case-control study was undertaken. Also studied were other potential risk factors namely: PID, undernutrition, blood group 'O', the use of IUD, prior abnormal pregnancies and prior abdominal surgery. The investigation included 72 cases diagnosed at the University of Health Sciences, Kansas City, Missouri from January 1, 1976 through December 31, 1987 and 72 pair-matched controls selected from live-birth deliveries at the same hospital. Univariable McNemar analyses revealed four strong risk factors: having ever smoked (OR = 2.1, p = 0.04), previous EP (OR = 14.3, p = 0.0001), previous fetal loss (OR = 4, p = 0.04) and previous pelvic and abdominal surgery (OR = 6.3 p = 0.0001). A stepwise logistic regression analysis using parity, eversmoking, underweight and PID was performed. Only PID remained strongly associated with EP after the first step (p = 0.009).