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Risk Factors for Ectopic Pregnancy

Three Part Question

In [pregnant women who present with PV bleeding to A&E] what are the [risk factors] for an [ectopic pregnancy]?

Clinical Scenario

A 24 year old woman presents to accident and emergency with vaginal bleeding. She tells you she did a home pregnancy test and it was positive. You want to assess her clinical risk of having an ectopic pregnancy.

Search Strategy

Medline 1966-06/05 using Ovid Interface
Embase 1980-06/05
CINAHL 1982-06/05
The Cochrane Library Issue 2, 2005
({[tubal or exp PREGNANCY, TUBAL or ectopic exp or PREGNANCY, ECTOPIC or abdominal or exp PREGNANCY, ABDOMINAL or extrauterine] AND [risk or exp Risk Factors or risk or exp Risk Assessment or or exp RISK]} LIMIT to humans and english)
Cochrane ('ectopic pregnancy' or 'tubal pregnancy') AND 'risk factors'

Search Outcome

997 papers were identified from medline or which 8 were relevant. 3 meta-analyses were found
No additional papers found from the other databases

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Anorlu RI. Oluwole A. Abudu OO. Adebajo S
2005 Feb
Cases;100 consecutive patients who had laparotomy for ectopic pregnancy in 1 of three hospitals Controls;280 randomly selected consenting women who attended the family planning and gynaecology clinics at the same hospitals as the patientsCase-control study (3b)Risk factorsAdjusted odds ratio (95% CI): Miscarriage 3.35 (1.93-5.83), Induced abortion 14.71 (5.57-27.96), Complicated induced abortion 4.13 (3.14-7.29), Previous pelvic surgery 2.09 (1.07-3.83), Previous EP 1.2 (0.47-7.2), Infertility treatment 1.69 (0.78-3.56), IUCD 3.76 (2.12-6.69), 15-19 years (sexual debut) 1.93 (1.71-2.93), Multiple sexual partners 3.2 (1.67-5.01) STD 9.06 (4.57-18.59) and PID 5.61 (3.64-10.52)These risk factors have been found in women from Nigeria.
Bunyavejchevin S. Havanond P. Wisawasukmongchol W
2003 Jun
208 cases of ectopic pregnancy and 781 controlsCase-control study (3b)Risk factorsOdds ratio (95% CI): Sexual partners >1 3.02 (1.75-5.23), Hx of PID 3.17 (1.40-7.19), Smoking 2.49 (1.36-4.58), Infertility 2.74 (1.35-5.54)Population studied was Thai women only
Bouyer J. Coste J. Shojaei T. Pouly JL. Fernandez H. Gerbaud L. Job-Spira N
2003 Feb 1
United States
803 cases of ectopic pregnancy 2 controls; a woman who gave birth at the same centre at which the case was treated and a woman whose delivery occured shortly after treatment of the case.Case-control study (3b)Risk factorsOdds ratio (95% CI): Age; 30-34 1.3 (1.0-1.7), 35-39 1.4 (1.0-2.0), >40 2.9 (1.4-6.1), Smoking: Past 1.5 (1.1-2.2), 1-9/day 1.7 (1.2-2.4), 10-19/day 3.1 (2.2-4.3), >20/day 3.9 (2.6-5.9), Prior spontaneous abortion: 1-2 1.2 (0.9-1.6), >2 3.0 (1.3-6.9), Prior induced abortion: Surgical 1.1 (0.8-1.6), Medical (or medical and surgical) 2.8 (1.1-7.2), Appendectomy (ruptured appendix) 1.4 (0.8-2.4), Prior STD: without salpingitis 1.0 (0.8-1.3), with probable PID 2.1 (0.8-5.4), confirmed PID 3.4 (2.4-5.0), Prior tubal surgery 4.0 (2.6-6.1), Previous use of OC 0.7 (0.5-1.0), Previous IUD 1.3 (1.0-1.8), Infertility: <1 year 2.1 (1.2-3.6), 1-2 years 2.6 (1.6-4.2) and >2 years 2.7 (1.8-4.2)This study was carrid out on french women only
Garrett AM. Vukov LF
1996 Feb
United States
Medical records of all patients with ectopic pregnancy who presented from 1986 through 1992 to the emergency department of a large, rural referral hospital with 65,000 annual visits (n=126)Retrospective case reviewRisk factorsPrior tubal surgery 38%, Hx of infertility 35%, PID 17%, Previous EP 16%, Appendectomy/pelvic operation 13%, Fertility drugs 9% & IUD in situ 1%Data collection was retrospective No odds ratios calculated
Single risk factor: 17%
No risk factor: 47%
Ankum WM. Mol BW. Van der Veen F. Bossuyt PM.
1996 Jun
Untied States
A total number of 6,718 cases of EP in 27 case control studies and 13,049 exposed women in 9 cohort studiesMeta-analysisRisk factors (cohort studies)Common odds ratio (95% CI): Pelvic and/or abdominal surgery 1.5 (1.1-2.6), In utero DES-exposure 5.6 (2.4-13), PID 5.7 (2.5-13), Medical abortion 1.2 (0.78-1.2), Infertility 2.0 (1.2-3.4)Individual papers do not provide sufficient data to allow multivariate analysis They did not look at contraceptive methods
Risk factors not covered by the cohort studies (case-control, with pregnant controls)Common odds ratio (95% CI): Previous; Gonorrhoea 2.9 (1.9-4.4), Chlamydia: IgG>1:32 2.8 (2.0-4.0), IgG>1:64 3.7 (2.9-4.7), Ectopic pregnancy 8.3 (6.0-11.5), Tubal surgery 21 (9.3-47), Tubal pathology 3.5, Current smoking 2.3 (2.0-2.8), Ever smoking 2.5 (1.8-3.4), Vaginal douching 1.1, Lifetime no. sexual partners >1 2.1 (1.4-4.8), Age at first sexual intercourse <18 1.6 (1.1-2.5)
Mol BW. Ankum WM. Bossuyt PM. Van der Veen F
Case-control and cohort studies published between 1978 and 1994 in English, French, German and Dutch were retrieved by a search in Medline, a hand-search on recent medical journals and cross-referencesMeta-analysisRisk factors (pregnant controls)Common Odds Ratios (95% CI): Oral contraception: current use 1.8 (0.9-3.4), IUCD: current use 4.2-45, past use 1.6 (1.4-1.8), Sterilization: 9.3 (4.9-18), Condom: 0.97 (0.24-4.0)No common odds ratio could be calculated for current IUCD use
P values: Oral contraception current use 0.502, IUCD current use 0.001, past use 0.849, sterilization 0.753
Xiong, X. Buekens, P. Wollast, E
From 1977 through 1994, 19 publications regarding 16 studies of ectopic pregnancy and IUD use were found by MEDLINE and manual searchMeta-analysisCurrent IUD use as a risk for ectopic pregnancy (pregnant controls)Pooled odds ratio: 10.63, 95% CI: 7.66-14.74 (p<0.01)
Past IUD use as a risk factor for ectopic pregnancy (pregnant controls)Pooled odds ratio: 1.33, 95% CI: 1.08-1.63


Originally only papers that looked at risk factors as a whole, as opposed to papers that looked at individual risk factors were going to be included in this bet. However because the meta-analysis did not report on contraceptive methods as a risk factor, two further meta-analyses had to be included. These reported on the risks associated with contraception as a whole and use of an IUD. When pregnant and non-pregnant controls were used, the odds ratios associated with the pregnant controls are used. This is because an A&E physician has to determine the risk of a pregnant woman having an ectopic gestation.

Clinical Bottom Line

There are numerous risk factors associated with an ectopic pregnancy they are (followed by the range of odds ratios): Pelvic inflammatory disease 3.17-5.7, Infertility 2.0-2.74, In utero DES exposure 5.6, Tubal surgery 4.0-21, Current smoking, 1.7-6.0 Previous ectopic pregnancy 1.2-8.3, Multiple sexual partners 2.1-3.2, Current IUD use 4.2-45, Sterilization 9.3 and Previous abortion 0.95-14.71


  1. Anorlu RI. Oluwole A. Abudu OO. Adebajo S Risk factors for ectopic pregnancy in Lagos, Nigeria. Acta Obstetricia et Gynecologica Scandinavica 2005;84(2):184-8
  2. Bunyavejchevin S. Havanond P. Wisawasukmongchol W Risk factors of ectopic pregnancy Journal of the Medical Association of Thailand 2003; 86 Suppl 2:S417-21
  3. Bouyer J. Coste J. Shojaei T. Pouly JL. Fernandez H. Gerbaud L. Job-Spira N Risk factors for ectopic pregnancy: a comprehensive analysis based on a large case-control, population-based study in France American Journal of Epidemiology 2003;157(3):185-94
  4. Anonymous Risk factor for ectopic pregnancy Canadian Family Physician 1999;45:300, 309-10
  5. Garrett AM. Vukov LF Risk factors for ectopic pregnancy in a rural population Family Medicine 1996;28(2):111-3
  6. Ankum WM. Mol BW. Van der Veen F. Bossuyt PM. Risk factors for ectopic pregnancy: a meta-analysis Fertility & Sterility 1996;65(6):1093-9
  7. Mol BW. Ankum WM. Bossuyt PM. Van der Veen F Contraception and the risk of ectopic pregnancy: a meta-analysis Contraception 1995;52(6):337-41
  8. Xiong, X. Buekens, P. Wollast, E IUD use and the risk of ectopic pregnancy: a meta-analysis of case-control studies Contraception 1995;52(1):23-34