What does a human chorionic gonadotropin (HCG) level of 0.5 and then 2 indicate in a sexually active female of reproductive age who had intercourse and took emergency contraception (levonorgestrel)?

HCG Levels of 0.5 and 2 After Emergency Contraception: Interpretation

These HCG levels of 0.5 and 2 mIU/mL are both negative for pregnancy and indicate that the emergency contraception (I-pill/levonorgestrel) was successful in preventing pregnancy. 1, 2

Understanding These HCG Values

• HCG levels below 5 mIU/mL are considered negative for pregnancy, and both values (0.5 and 2) fall well below this threshold 1, 2
• The slight increase from 0.5 to 2 is clinically insignificant and remains within the normal non-pregnant range—this minimal fluctuation does not indicate pregnancy 1, 2
• True early pregnancy would show HCG levels rising rapidly (typically doubling every 48-72 hours), reaching levels of 25-50 mIU/mL or higher within days of implantation 1, 2

What This Means Clinically

• The emergency contraception worked effectively to prevent pregnancy after the unprotected intercourse 1, 2, 3
• Levonorgestrel emergency contraception has approximately 75% effectiveness when taken within 72 hours of unprotected intercourse, and these results confirm successful prevention 2, 4
• No pregnancy exists based on these laboratory values 1, 2

Important Follow-Up Considerations

• A menstrual period should occur within 3 weeks after taking emergency contraception; if it doesn't arrive, repeat pregnancy testing is warranted 5
• Resume or start regular contraception immediately after levonorgestrel use, using a barrier method or abstaining for 7 consecutive days after restarting hormonal contraception 1, 2
• If regular contraception is not already in place, consider long-acting reversible contraceptives (LARC) such as IUDs or implants, which have failure rates below 1% and don't rely on patient adherence 6, 1

Common Pitfall to Avoid

• Do not misinterpret minimal HCG fluctuations in the 0-5 range as indicating pregnancy—only values consistently above 5 mIU/mL, particularly those that double appropriately, suggest pregnancy 1, 2
• Some assays can detect trace amounts of HCG that have no clinical significance; the threshold of 5 mIU/mL exists specifically to avoid false positive interpretations 1, 2