Risk Factors for Ectopic Pregnancy
The most significant risk factors for ectopic pregnancy include history of tubal surgery, previous salpingitis, and previous ectopic pregnancy, with tubal damage being the primary underlying mechanism for increased risk. 1, 2
Major Risk Factors
Tubal Factors (Highest Risk)
- History of tubal surgery (including sterilization) 1, 2
- Previous salpingitis/pelvic inflammatory disease (risk doubles with each recurrent episode) 1, 3
- Previous ectopic pregnancy (significantly increases risk due to surgical management or persistence of original risk factors) 1, 4
- Tubal damage from any cause (OR = 2.7) 4
Reproductive History
- Previous infertility (AOR = 2.18) 3
- In vitro fertilization and assisted reproduction (particularly in women with tubal factor infertility, AOR = 8.99) 1, 2, 3
- Multiple prior pregnancies (increased gravidity, OR = 1.50) 4
- Prior spontaneous abortions (OR = 1.93) 4
Contraceptive Failures
- Current IUD use (AOR = 16.43 when pregnancy occurs with IUD in place) 3
- Previous IUD use (AOR = 1.72) 3
- Failed contraception including:
- Oral contraceptive pills (AOR = 3.02)
- Levonorgestrel emergency contraception (AOR = 4.75)
- Female sterilization (AOR = 4.73) 3
Surgical History
Infection History
- Previous Chlamydia trachomatis infection (AOR = 3.18) 3
Demographic and Lifestyle Factors
Clinical Implications
It's important to note that while these risk factors are significant, many women who develop ectopic pregnancy have no identifiable risk factors 5. Therefore, clinicians should maintain a high index of suspicion for ectopic pregnancy in any woman of reproductive age presenting with abdominal pain and/or vaginal bleeding in early pregnancy.
Risk Reduction Strategies
Some risk factors are potentially modifiable:
- Smoking cessation
- Early diagnosis and effective treatment of pelvic infections
- Careful surgical technique during tubal procedures
- Consideration of alternative contraceptive methods in women with multiple risk factors 2
Monitoring High-Risk Patients
Women with multiple risk factors should receive:
- Early pregnancy confirmation
- Prompt transvaginal ultrasound to confirm intrauterine pregnancy
- Serial β-hCG measurements when ultrasound is inconclusive
- Close monitoring during fertility treatments, especially IVF-ET in women with tubal factor infertility 2, 3
Understanding these risk factors allows for earlier diagnosis and intervention, which is critical as ectopic pregnancy remains a leading cause of maternal mortality in the first trimester 7.