Best Contraceptive to Prevent Ectopic Pregnancy
Both IUDs and OCPs significantly reduce the absolute risk of ectopic pregnancy compared to no contraception, but IUDs—particularly the levonorgestrel-releasing IUD—provide superior protection against ectopic pregnancy compared to oral contraceptive pills.
Absolute Risk Reduction: Both Methods Protective
All effective contraceptives reduce ectopic pregnancy risk by preventing pregnancy altogether; the absolute risk of ectopic pregnancy is lower in women using any contraception compared to those using none 1, 2.
IUDs are among the most effective contraceptives available, with failure rates less than 1% per year, meaning fewer total pregnancies and therefore fewer opportunities for ectopic pregnancy 3, 4.
OCPs have higher typical-use failure rates (approximately 7-9% per year with typical use) compared to IUDs, resulting in more total pregnancies and thus more potential ectopic pregnancies in absolute terms 3.
Comparative Effectiveness: IUD Superior
Levonorgestrel-Releasing IUD (LNG-IUD)
The LNG-IUD provides the strongest protection against ectopic pregnancy with an ectopic pregnancy rate of only 0.02 per 100 woman-years 5.
In a large prospective European study of 58,324 women, the LNG-IUD demonstrated an adjusted hazard ratio of 0.26 (95% CI: 0.10-0.66) for ectopic pregnancy compared to copper IUDs, meaning a 74% lower risk 6.
The overall Pearl pregnancy index for LNG-IUD is 0.06 (95% CI: 0.04-0.09), making it one of the most effective contraceptives available 6.
Copper IUD
Copper IUDs also provide excellent protection with approximately 6 pregnancies per 1000 woman-years, and ectopic pregnancies are rarer in copper IUD users than in women using no contraception 1.
The ectopic pregnancy incidence with copper IUDs ranges from 0-2.9 per 1000 woman-years in marketed devices 7.
Among pregnancies that do occur with copper IUDs in place, approximately 1 in 20 (5%) is ectopic, but the absolute risk remains very low due to the high overall effectiveness 1.
Oral Contraceptive Pills
OCPs reduce ectopic pregnancy risk primarily by preventing ovulation, but their effectiveness depends heavily on consistent, correct use 3.
No specific data on ectopic pregnancy rates with OCPs were provided in the guidelines, but their higher typical-use failure rate (compared to IUDs) translates to more total pregnancies and therefore more ectopic pregnancies in absolute numbers 3.
Clinical Recommendation Algorithm
For women specifically concerned about ectopic pregnancy prevention:
First-line choice: Levonorgestrel-releasing IUD - provides the lowest absolute risk of ectopic pregnancy (0.02 per 100 woman-years) 5, 6
Second-line choice: Copper IUD - also highly protective with ectopic pregnancy rates of 0-2.9 per 1000 woman-years 7
Third-line choice: OCPs - protective compared to no contraception, but less effective than IUDs due to higher typical-use failure rates 3
Important Clinical Caveats
Past ectopic pregnancy is NOT a contraindication to IUD use (Category 1 for both copper and LNG-IUD), and women with this history can safely use IUDs 3, 1.
The comment that "when pregnancy occurs with an IUD, the relative likelihood of ectopic pregnancy increases" refers only to the proportion among the rare pregnancies that do occur—not the absolute risk, which remains very low 3.
IUDs do not cause ectopic pregnancy; they prevent all pregnancies, including ectopic ones, more effectively than most other methods 1, 2.
Progestin-only injectables and implants also provide excellent protection against ectopic pregnancy with incidence rates of 0-2.9 per 1000 woman-years, comparable to IUDs 7.