Risk factors for ectopic pregnancy: a case-control study

Aust N Z J Obstet Gynaecol. 2006 Dec;46(6):521-7. doi: 10.1111/j.1479-828X.2006.00653.x.


Aim: To identify the risk factors for ectopic pregnancy.

Methods: We conducted a prospective case-control study for the role of several risk factors in the occurrence of ectopic pregnancy in Turkey. A total of 225 cases and 375 controls were compared for sociodemographic characteristics, cigarette smoking, obstetric, gynaecological, surgical histories, the presence or absence of assisted conception and contraceptive usage.

Results: The main risk factors for ectopic pregnancy were prior ectopic pregnancy (adjusted odds ratio (AOR): 13.1) and a history of infectious reproductive system (AOR for pelvic inflammatory disease: 6.8). Other risk factors found to be associated with an increased risk for ectopic pregnancy were multisexual partner (AOR: 3.5), history of infertility (AOR: 2.5), induced conception cycle (AOR: 3.4), current intrauterine device usage (AOR: 3.2), prior Caesarean section (AOR: 2.1) and cigarette smoking at the time of conception (AOR=1.7). On the contrary, barrier methods were protective from ectopic pregnancy (AOR: 0.4).

Conclusions: The increased awareness and knowledge of risk factors have enabled an early and accurate diagnosis of ectopic pregnancy. This study has found prior pelvic infection to be a major aetiological factor for ectopic pregnancy. Furthermore, other factors found to be associated with ectopic pregnancy, such as prior ectopic pregnancy, infertility history and induced conception cycle, may be the result of a previous pelvic infection that may cause tubal sequelae. These factors are potential targets for intervention and modification.

MeSH terms

  • Adult
  • Case-Control Studies
  • Cesarean Section
  • Contraceptives, Oral
  • Developing Countries
  • Female
  • Humans
  • Infertility, Female
  • Intrauterine Devices
  • Middle Aged
  • Pregnancy
  • Pregnancy, Ectopic / epidemiology*
  • Prospective Studies
  • Risk Factors
  • Sexual Partners
  • Sexually Transmitted Diseases
  • Turkey / epidemiology


  • Contraceptives, Oral