Ectopic Pregnancy Risk with Paragard (Copper IUD)
The absolute risk of ectopic pregnancy with Paragard is extremely low due to the IUD's high contraceptive effectiveness, but when pregnancy does occur with an IUD in place, the relative likelihood of ectopic pregnancy increases dramatically—approximately 1 in 20 pregnancies (5%) occurring with an IUD will be ectopic. 1, 2, 3
Understanding the Paradox
The key to counseling patients is distinguishing between absolute and relative risk:
Absolute risk is extremely low: Copper IUDs reduce the overall risk of ectopic pregnancy by 91% compared to women using no contraception 4. The overall pregnancy rate with copper IUDs is less than 1% annually, with a Pearl index of 0.52 per 100 woman-years 5.
Relative risk increases when pregnancy occurs: Among the rare pregnancies that do occur with an IUD in place, approximately 5% (1 in 20) are ectopic 3. This represents a greatly increased relative likelihood compared to the general pregnant population 1, 2.
Clinical Implications
Immediate Evaluation Required
Any woman with an IUD who has a positive pregnancy test must be evaluated immediately to rule out ectopic pregnancy first, given the dramatically increased relative risk. 2
Management Algorithm When Pregnancy Occurs
Remove the IUD as soon as possible if strings are visible or the device is in the cervical canal to reduce risks of spontaneous abortion, septic abortion, preterm delivery, and chorioamnionitis 2, 6.
If the IUD cannot be safely removed, counsel patients about significantly increased risks: 8 in 10 pregnancies with a levonorgestrel IUD left in place end in spontaneous abortion, and only 25% of pregnancies with any IUD left in situ result in live birth compared to 90% when removed 2, 3.
Instruct patients to return promptly for heavy bleeding, cramping, pain, abnormal vaginal discharge, or fever after IUD removal 2.
Comparative Effectiveness
The levonorgestrel IUD (Mirena) demonstrates even lower ectopic pregnancy rates than copper IUDs, with an adjusted hazard ratio of 0.26 (95% CI: 0.10-0.66) for ectopic pregnancy compared to copper devices 5.
Contraindications and Special Populations
Past ectopic pregnancy is NOT a contraindication to copper IUD use (Category 1—no restriction) because the absolute risk remains extremely low despite the device's high effectiveness 1.