Prior condom use and the risk of tubal pregnancy.

The relationship between prior condom use and tubal pregnancy was assessed in a population-based case-control study at Group Health Cooperative of Puget Sound during 1981-86. We interviewed 227 women with a tubal pregnancy who had no clinical indication of infertility and no history of sterilization and 674 similarly defined controls who were matched to the cases on age and county of residence. A history of condom use for more than one year was associated with a decreased risk of subsequent tubal pregnancy (RR = 0.74, 95% CI = 0.44, 1.26) adjusted for the effects of age, current use of contraceptive methods, educational level, and age at first intercourse. The effect was more pronounced when condoms had been used during five-year periods with more than one partner (RR = 0.38, 95% CI = 0.15, 1.0) than during five-year periods with one partner (RR = 0.89, 95% CI = 0.45, 1.76). Condom use for less than one year was unrelated to risk of ectopic pregnancy. Since the use of condoms offers protection against sexually transmitted diseases, one or more of which are likely to be causally related to tubal pregnancy, the observed negative association plausibly represents a protective influence of long-term condom use on the occurrence of tubal pregnancy.