Duphaston Dose for Threatened Abortion
For threatened abortion (threatened miscarriage), the recommended dosage of dydrogesterone (Duphaston) is 40 mg orally as a loading dose, followed by 10 mg three times daily (30 mg/day total maintenance dose), continued until one week after bleeding stops or until 12-14 weeks of gestation, whichever is longer.
Evidence-Based Dosing Regimen
The most robust evidence comes from randomized controlled trials specifically examining dydrogesterone for threatened miscarriage 1, 2, 3, 4. The standard protocol involves:
- Loading dose: 40 mg orally (single dose)
- Maintenance dose: 10 mg orally three times daily (TID)
- Duration: Continue until 1 week after vaginal bleeding stops, OR until 12-14 completed weeks of gestation, whichever is longer
- Maximum duration: Up to 14 weeks of gestation if bleeding persists
Clinical Context and Efficacy Considerations
The evidence for dydrogesterone in threatened miscarriage is mixed and controversial. Two recent high-quality randomized controlled trials showed conflicting results:
- A 2021 trial found no significant benefit: miscarriage rate was 12.8% with dydrogesterone versus 14.3% with placebo (not statistically significant) 1
- A 2024 trial similarly showed no significant difference: 90% continuing pregnancy with dydrogesterone versus 86% with placebo 2
- However, an earlier 2009 study suggested benefit: 17.5% miscarriage rate with dydrogesterone versus 25% without treatment 4
Despite limited efficacy evidence, if you choose to prescribe dydrogesterone for threatened miscarriage, use the dosing regimen above, as this is the protocol tested in clinical trials.
Important Clinical Caveats
When to Consider Treatment
- Vaginal bleeding in first trimester (6-12 weeks gestation)
- Viable intrauterine pregnancy confirmed on ultrasound
- Patient has history of recurrent pregnancy loss (stronger rationale)
Safety Profile
- Generally well-tolerated with minimal side effects 1, 2
- Recent safety concern: A 2025 pharmacovigilance analysis found increased reporting of birth defects, particularly hypospadias and congenital heart defects, associated with dydrogesterone exposure (ROR 5.4 compared to other drugs) 5
- This represents a possible safety signal requiring further investigation
Alternative Considerations
The evidence base is stronger for vaginal micronized progesterone in certain populations:
- For women with history of recurrent pregnancy loss: vaginal micronized progesterone 400 mg twice daily shows better evidence 6
- Micronized progesterone is considered first-line by some guidelines for luteal phase support 7
Practical Algorithm
Step 1: Confirm threatened miscarriage diagnosis
- Vaginal bleeding in first trimester
- Viable intrauterine pregnancy on ultrasound
- Gestational age 6-12 weeks
Step 2: Assess risk factors
- History of recurrent pregnancy loss? → Stronger indication for treatment
- First episode of bleeding? → Weaker evidence for benefit
Step 3: If prescribing dydrogesterone:
- Give 40 mg loading dose immediately
- Prescribe 10 mg TID for maintenance
- Continue until 1 week post-bleeding cessation or 12-14 weeks gestation
- Counsel patient about limited efficacy evidence and emerging safety concerns
Step 4: Follow-up
- Monitor bleeding pattern
- Repeat ultrasound at 8-10 weeks and 12-14 weeks
- Discontinue if miscarriage confirmed or if reaches 14 weeks with viable pregnancy
Critical Warning
The evidence does NOT strongly support routine use of dydrogesterone for threatened miscarriage. Recent high-quality trials show no significant benefit 1, 2, and emerging safety signals regarding birth defects warrant caution 5. Consider this treatment only after shared decision-making with the patient, particularly in women with recurrent pregnancy loss where there may be greater potential benefit.