Gestational Age Limits for Medication Abortion
The abortion pill (mifepristone followed by misoprostol) can be used up to 77 days (11 weeks) of gestation for medication abortion, though some evidence supports use up to 84 days (12 weeks) for early pregnancy loss. 1
Standard Gestational Age Limits
- Up to 63 days (9 weeks) of amenorrhea is the most commonly cited limit in clinical practice, with this timeframe supported by extensive research demonstrating high efficacy and safety 2, 3
- Up to 77 days (11 weeks) of gestation represents the current evidence-based upper limit for medication abortion specifically 1
- Up to 84 days (12 weeks) of gestation is supported for management of early pregnancy loss (miscarriage) using the same medication regimen 1
Efficacy by Gestational Age
- Before 9 weeks: Medical abortion can be performed safely in outpatient or home settings with complete abortion rates of 95-97% 4, 3
- 9-11 weeks: The medication regimen remains effective, though success rates may be slightly lower than earlier gestations 5, 1
- Second trimester (beyond 12 weeks): Labor induction abortion using mifepristone and misoprostol is effective throughout the second trimester, though this represents a different clinical scenario with different dosing protocols 6
Standard Dosing Regimen
- Mifepristone 200 mg orally followed by misoprostol 800 mcg administered buccally or vaginally 1
- The interval between medications can be simultaneous to 48 hours, with 24-48 hours being most common, though simultaneous administration has been shown equally effective 2, 3
- For second trimester procedures, mifepristone 200 mg is followed by misoprostol 24-48 hours later, with 95% of abortions complete within 24 hours of misoprostol administration 6
Important Clinical Considerations
Gestational age determination is critical and should be established using:
- Ultrasonography when available and clinically indicated 1
- Menstrual history when ultrasonography cannot be confirmed or when there are no risk factors for ectopic pregnancy 1
- Ultrasonography is specifically needed when gestational dating cannot be confirmed using clinical data alone or when risk factors for ectopic pregnancy exist 1
Key Safety Points
- Contraindications: Misoprostol should be avoided in women with previous cesarean delivery due to risk of uterine rupture 7
- Expected effects: Cramping and bleeding are normal, with bleeding lasting an average of 9-16 days 1
- Rare complications include ongoing pregnancy, infection, hemorrhage, undiagnosed ectopic pregnancy, and need for unplanned uterine aspiration 1
Access Considerations
- The Society for Maternal-Fetal Medicine supports access to abortion without unnecessary barriers, including via telemedicine 8
- When requiring in-person testing would delay or limit abortion access, the priority is completing the abortion, with patients counseled on potential implications 8
- Mifepristone and misoprostol can be offered in ambulatory settings without special equipment or on-site emergency services given their safety profile 5