How Long Does hCG Take to Drop After Miscarriage?
Most standard urine pregnancy tests (sensitivity 20-25 mIU/mL) will become negative within 2 weeks after a miscarriage, though serum hCG levels follow a predictable exponential decline with a half-life of approximately 1.3 days in urine and 0.63-3.85 days in serum. 1, 2
Expected Timeline for hCG Decline
Standard Miscarriage (Non-Molar)
The rate of hCG decline depends heavily on the initial hCG level at the time of pregnancy loss:
- By 2 days post-miscarriage: hCG should decline by 21-35% (faster decline with higher initial values) 3
- By 7 days post-miscarriage: hCG should decline by 60-84% (again, dependent on starting concentration) 3
- By 2 weeks post-miscarriage: Most urine pregnancy tests will be negative 1, 2
- By 4 weeks post-miscarriage: A persistently positive test suggests retained products of conception or persistent trophoblast 2
After Medical Abortion (Specific Data)
For women undergoing complete medical abortion, the decline follows a more predictable pattern 4:
- Day 3: Mean decline of 70% (range 37-99%) 4
- Day 5: Mean decline of 91% (range 68-98%) 4
- Days 7-9: Mean decline of 97% (range 92-99%) 4
- Days 12-14: Mean decline of 99% (range 87-100%) 4
Critical Warning Signs
A decline rate less than 21% at 2 days or less than 60% at 7 days suggests retained products of conception or ectopic pregnancy and requires further evaluation. 3
When to Suspect Complications
- Plateauing hCG levels (less than 15% change over 48 hours for two consecutive measurements) 5
- Rising hCG levels after initial decline 1
- Positive urine test at 4 weeks post-miscarriage 2
Special Consideration: Molar Pregnancy
After molar pregnancy, hCG monitoring must continue much longer—up to 6 months—due to risk of gestational trophoblastic neoplasia. 1, 6
The monitoring protocol differs significantly 7, 6:
- Check hCG at least every 2 weeks until normalization 7, 6
- For partial molar pregnancy: One additional normal hCG value required before discharge 7, 6
- For complete molar pregnancy: Monthly hCG monitoring for up to 6 months 7, 6
- Plateauing or rising levels indicate development of gestational trophoblastic neoplasia 7, 6
Clinical Pitfalls to Avoid
Do not assume complete miscarriage based on history and ultrasound alone—approximately 6% of women with apparent complete miscarriage have underlying ectopic pregnancy. 8
Essential Management Points
- Always obtain serial hCG measurements rather than relying on a single value 3, 8
- Use the same laboratory for serial measurements, as different assays have varying sensitivities 6
- Consider retained products if hCG decline is slower than expected 1, 3
- Qualitative pregnancy tests can remain positive for several weeks after pregnancy termination because hCG persists 1, 6
When Follow-Up Is Safe to Discontinue
Healthcare providers can be reasonably certain a woman is not pregnant if she is ≤7 days after spontaneous or induced abortion. 1
However, this applies to contraception initiation decisions, not to ruling out complications like retained products or ectopic pregnancy, which require documented hCG decline to undetectable levels (typically <5 mIU/mL) 8.