title: Using induced abortion to measure contraceptive efficacy.
abstract: Data from a 1989-1990 case-control study of contraceptive efficacy in Norway compare contraceptive use among women who requested an abortion (1,386 cases) with women who responded to a general fertility survey (2,627 controls). In a logistic regression analysis measuring contraceptive efficacy as the odds of avoiding a pregnancy that terminated in an induced abortion compared with the odds for nonuse, consistent condom use was found to lower fecundity by 88.9%, diaphragm use by 89.3%, the pill by 97.8%, the IUD by 97.6%, vasectomy by 99.5%, and female sterilization by 99.8%. The relative contraceptive efficacy of the condom, the IUD and the pill did not vary by marital status or parity but did vary with age; the proportion by which each of these methods reduced fecundity declined among successively older age-groups.
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital of Trondheim, Norway.
authors.forename: F E
authors.initials: FE
authors.lastname: Skjeldestad
mesh_terms: D000028:Abortion, Induced; D000328:Adult; D015331:Cohort Studies; D003268:Contraception Behavior; D003273:Contraceptive Devices / Q000706:statistics & numerical data; D005260:Female; D005298:Fertility; D006801:Humans; D008875:Middle Aged; D009664:Norway; D011247:Pregnancy