title: Ectopic pregnancy and emergency contraceptive pills: a systematic review.
abstract: OBJECTIVE
  To evaluate the existing data to estimate the rate of ectopic pregnancy among emergency contraceptive pill treatment failures.
  
  
  METHODS
  Our initial reference list was generated from a 2008 Cochrane review of emergency contraception. In August 2009, we searched Biosys Previews, the Cochrane Database of Systematic Reviews, Medline, Global Health Database, Health Source: Popline, and Wanfang Data (a Chinese database).
  
  
  METHODS
  This study included data from 136 studies, which followed a defined population of women treated one time with emergency contraceptive pills (either mifepristone or levonorgestrel) and in which the number and location of pregnancies were ascertained.
  
  
  RESULTS
  Data from each article were abstracted independently by two reviewers. In the studies of mifepristone, 3 of 494 (0.6%) pregnancies were ectopic; in the levonorgestrel studies, 3 of 307 (1%) were ectopic.
  
  
  CONCLUSIONS
  The rate of ectopic pregnancy when treatment with emergency contraceptive pills fails does not exceed the rate observed in the general population. Because emergency contraceptive pills are effective in lowering the risk of pregnancy, their use will reduce the chance that an act of intercourse will result in ectopic pregnancy.
  
  
  METHODS
  III.
authors.affiliation: From Office of Population Research, Princeton University, Wallace Hall, Princeton, New Jersey; Family Health International, Research Triangle Park, North Carolina; The Hull York Medical School, University of Hull, United Kingdom; Shanghai Institute of Planned Parenthood Research, Shanghai, People's Republic of China; Minhang Central Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China.
authors.forename: Kelly
authors.initials: K
authors.lastname: Cleland
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Raymond
authors.forename: James
authors.initials: J
authors.lastname: Trussell
authors.forename: Linan
authors.initials: L
authors.lastname: Cheng
authors.forename: Haoping
authors.initials: H
authors.lastname: Zhu
mesh_terms: D003281:Contraceptives, Postcoital; D005260:Female; D006801:Humans; D016912:Levonorgestrel; D015735:Mifepristone; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000453:epidemiology*
chemical_list: D003281:Contraceptives, Postcoital; D015735:Mifepristone; D016912:Levonorgestrel