Vaginal Progesterone Preparations Available
The primary vaginal progesterone preparations available are micronized progesterone (100-200 mg capsules/suppositories), progesterone gel (90 mg/8% gel), and vaginal tablets, with micronized progesterone 200 mg daily being the most commonly recommended formulation for endometrial protection and preterm birth prevention. 1, 2
Available Formulations
Micronized Progesterone
- Capsules/Suppositories: 100 mg or 200 mg daily
- Can be administered once daily (200 mg) or twice daily (100 mg)
- Used for both continuous (100 mg daily) and cyclic regimens (200 mg for 10-12 days per month) 1
- Specific products include Utrogestan (200 mg capsules) 2
- Important caveat: Many micronized progesterone capsules contain peanut oil in excipients and are contraindicated in patients with severe peanut allergies 3
Progesterone Gel
- 90 mg (8% gel) daily - most commonly studied formulation
Vaginal Tablets
- Endometrin: 100 mg tablets, typically administered twice daily 5, 6
- Less commonly used than capsules or gel
Clinical Context and Dosing
For Endometrial Protection (with estrogen therapy)
- Cyclic regimen: 200 mg micronized progesterone (oral or vaginal) for 12-14 days every 28 days 2
- Continuous regimen: 100 mg micronized progesterone daily 1
For Preterm Birth Prevention
- 200 mg micronized progesterone suppositories daily from diagnosis of short cervix (≤20-25 mm) until 36 weeks 4, 3
- 90 mg progesterone gel daily - alternative formulation with similar efficacy 4
- 100 mg suppositories nightly (less commonly used) 4
For Luteal Phase Support in ART
- 200 mg micronized progesterone capsules 2-3 times daily 7
- 90 mg progesterone gel (Crinone 8%) once daily 7
- 100 mg tablets (Endometrin) twice daily 6
Key Clinical Considerations
Advantages of vaginal administration over oral progestogens include:
- Fewer systemic side effects (mood swings, bloating, fluid retention) 1
- Avoidance of first-pass hepatic metabolism
- Direct endometrial delivery with adequate serum levels 1
Common pitfall: The evidence for vaginal progesterone efficacy varies by indication. While it has strong evidence for short cervix without prior preterm birth 3, the evidence is weaker for women with prior spontaneous preterm birth, where 17-hydroxyprogesterone caproate (intramuscular) shows stronger efficacy 8.
Product interchangeability: There is limited evidence that the 90 mg gel and 200 mg suppository formulations are directly interchangeable, though both have demonstrated efficacy in clinical trials 4. Studies comparing different preparations show similar pregnancy rates in ART cycles 9, 7.
Safety note: Vaginal progesterone has not been associated with increased risk of gestational diabetes 3, and contraindications include hormone receptor-positive breast cancer 3.