Contraception and ectopic pregnancy risk.

Studies of the association of ectopic pregnancy with contraception have generated a conflicting array of results because of methodologic differences between studies. We estimated the absolute incidence rates of ectopic pregnancy for various contraceptives by multiplying the pregnancy rate by the proportion of pregnancies with ectopic implantation for each method. Our results indicated a more than 500-fold difference in ectopic pregnancy incidence, from a low of 0.005 ectopic pregnancies per 1000 women years of oral contraception or vasectomy to a high of 2.6 per 1000 women years of no contraception. These estimated incidence rates should be useful for clinicians and patients seeking to better understand the risks and benefits of contraceptives.