What is the risk of ectopic pregnancy in a female patient of reproductive age using Paragard (intrauterine device, IUD) for emergency contraception?

Ectopic Pregnancy Rate with Paragard for Emergency Contraception

The copper IUD (Paragard) used for emergency contraception has an extremely low ectopic pregnancy rate of less than 1 per 1000 woman-years of use, making it one of the safest and most effective emergency contraceptive options available. 1, 2

Absolute Risk of Ectopic Pregnancy

• The copper IUD demonstrates a cumulative 4-year probability of ectopic pregnancy of only 4 per 1000 women (0.4%), based on large-scale surveillance data of over 35,000 women with 38,000 years of use 2
• When used for emergency contraception specifically, the copper IUD substantially reduces the overall risk of pregnancy, including ectopic pregnancy, when inserted within 5 days of unprotected intercourse 1, 3
• The typical use failure rate for the copper IUD is 0.8% within the first year, with perfect use failure of 0.6%, meaning the absolute number of pregnancies (including ectopic) is exceptionally low 1

Protective Effect vs. General Population

• The copper IUD actually protects against ectopic pregnancy compared to using no contraception, as it prevents pregnancy overall more effectively than it specifically prevents intrauterine pregnancy 1, 2
• The relative risk of ectopic pregnancy among copper IUD users compared to sexually active women not using hormonal contraception or sterilization was estimated to be below 1.0 in population-based studies 2
• Combined hormonal contraceptives are noted to protect against pregnancy in general, including ectopic gestation, and the same principle applies to the copper IUD 1

Important Clinical Context

If pregnancy does occur with a copper IUD in place, the proportion that are ectopic is higher than in the general pregnant population (approximately 3.4% of pregnancies with IUD in situ were ectopic in one series), but this reflects the IUD's superior prevention of intrauterine versus ectopic pregnancy, not an increased absolute risk 4

Key Distinction for Counseling:

• The copper IUD dramatically reduces the absolute risk of any pregnancy, including ectopic pregnancy 1, 2
• However, in the rare event that pregnancy occurs despite the IUD, clinicians must maintain higher suspicion for ectopic location 4
• This is fundamentally different from the IUD causing ectopic pregnancies—it prevents them, just not as completely as it prevents intrauterine pregnancies 1

Risk Factors to Consider

When counseling patients about emergency copper IUD insertion, assess for pre-existing ectopic pregnancy risk factors that are independent of the device itself:

• History of pelvic inflammatory disease or sexually transmitted infections (particularly Chlamydia trachomatis) 5, 6
• Previous ectopic pregnancy 1
• History of tubal surgery or endometriosis 5
• These factors increase baseline ectopic risk but are not contraindications to copper IUD use for emergency contraception 1, 3

Immediate Effectiveness

• The copper IUD is effective immediately upon insertion with no backup contraception required, making it superior to oral emergency contraceptive pills in both efficacy and duration of protection 3, 7
• It can be inserted at any time during the menstrual cycle if pregnancy can be reasonably excluded 3