title: Risk factors for ectopic pregnancy: A case-control study.
abstract: BACKGROUND
  Ectopic pregnancy (EP) is a condition presenting as a major health problem for women of childbearing age. This study aimed to identify potential risk factors for EP and to evaluate the contribution of the risk factors associated to EP.
  
  
  METHODS
  This retrospective nested case-control study was conducted from 2006 to 2011. In case group, there were a total of 83 women diagnosed with EP, while in the control group; there was a total of 340 women who gave birth. The basic recorded information included surgical, gynecological, obstetrics, sexual, contraceptive, and infectious histories; demographic characteristics; smoking habits; fertility markers; as well as reproductive outcome after EP. The association between EP and the factors studied was analyzed by logistic regression.
  
  
  RESULTS
  The findings reveal that the following factors were associated with increased risk of EP, including: Maternal age (odds ratio [OR] =1.11, confidence interval [CI] [1.06-1.16], P < 0.0001), spouse's cigarette smoking (OR = 1.73, CI [1.05-2.85], P = 0.02), gravidity (OR = 1.50, CI [1.25-1.80], P < 0.0001), prior spontaneous abortions (OR = 1.93, CI [1.11-3.36], P = 0.01), history of EP (OR = 17.16, CI [1.89-155.67], P = 0.01), tubal blockage (OR = 10.85, CI [2.02-58.08], P = 0.01), use of intrauterine device (IUD) (OR = 4.39, CI [1.78-10.81], P = 0.001), tubal damage (OR = 2.704, CI [1.26-5.78], P = 0.01), first pregnancy interval (OR = 1.01, CI [1.00-1.02], P < 0.0001) and history of infertility (OR = 6.13, CI [2.70-13.93], P < 0.0001).
  
  
  CONCLUSIONS
  By identifying risk factors being amenable to modification, such as cigarette smoking and use of IUD and first pregnancy interval the effective risk-reduction strategies can be devised.
authors.affiliation: Department of Endocrinology and Female Infertility at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran ; Department of Obstetrics and Gynecology, Tehran University of Medical Sciences, Tehran, Iran ; Department of Gynecology and Obstetrics, Arash Women's Health Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Moini
authors.affiliation: Department of Gynecology and Obstetrics, Arash Women's Health Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Reihaneh
authors.initials: R
authors.lastname: Hosseini
authors.affiliation: Department of Endocrinology and Female Infertility at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran.
authors.forename: Nadia
authors.initials: N
authors.lastname: Jahangiri
authors.affiliation: Department of Endocrinology and Female Infertility at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Shiva
authors.affiliation: Department of Statistics, Faculty of Mathematical Science and Computer, Shahid Chamran University, Ahwaz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Akhoond
keywords: Ectopic pregnancy; intrauterine device; tubal damage