What is the recommended dosage and regimen for using progesterone (a steroid hormone) for therapeutic purposes, such as supporting pregnancy or managing menstrual irregularities?

Progesterone Dosage and Regimen for Therapeutic Use

For prevention of preterm birth in women with singleton pregnancies and prior spontaneous preterm birth, 17-alpha-hydroxyprogesterone caproate (17P) 250 mg intramuscularly weekly from 16-20 weeks until 36 weeks gestation is the recommended regimen. 1

Preterm Birth Prevention

Singleton Pregnancies with Prior Spontaneous Preterm Birth (SPTB)

• 17-alpha-hydroxyprogesterone caproate (17P) 250 mg IM weekly
  • Start: 16-20 weeks gestation
  • End: 36 weeks gestation
  • Efficacy: 34% reduction in recurrent preterm birth 1

Singleton Pregnancies without Prior SPTB but Short Cervix

• For women with cervical length ≤20 mm at 24 weeks:
  • Vaginal progesterone 90 mg gel OR
  • Vaginal progesterone 200 mg suppository daily
  • Continue until 36 weeks gestation 1, 2

Multiple Gestations

• No evidence of effectiveness for progesterone therapy in multiple gestations (twins, triplets) 1
• Not recommended for routine use

Secondary Amenorrhea Treatment

• Oral progesterone 400 mg daily at bedtime for 10 days 3
• Administration: Take with a glass of water while standing
• Expected outcome: 80% of women experience withdrawal bleeding within 7 days of completing treatment 2
• Important caution: May cause drowsiness, dizziness, and blurred vision; take at bedtime 3

Prevention of Endometrial Hyperplasia in Women Taking Estrogen

• Oral progesterone 200 mg daily at bedtime for 12 days per 28-day cycle 3
• For postmenopausal women with an intact uterus who are receiving daily conjugated estrogens 2, 3
• Natural micronized progesterone has a better safety profile than synthetic progestins, with lower risk of breast cancer and no negative impact on cholesterol, carbohydrate metabolism, or blood pressure 2, 4

Threatened Miscarriage

• For women with early pregnancy bleeding and previous miscarriage(s):
  • Vaginal micronized progesterone 400 mg twice daily
  • Start: At presentation with bleeding
  • Continue until 12 weeks gestation (evidence suggests benefit is complete by 12 weeks) 5, 6
  • Note: Some guidelines recommend continuing until 16 weeks, but this duration is not evidence-based 5

Important Contraindications and Precautions

• Do not use progesterone in patients with:
  • Known or suspected pregnancy (when used for non-pregnancy indications)
  • Undiagnosed vaginal bleeding
  • Active thromboembolic disorders
  • History of arterial thrombotic disease
  • Current or history of hormone-dependent cancers
  • Liver problems
  • Peanut allergy (for formulations containing peanut oil) 2, 3

Administration Considerations

• Oral progesterone should be taken at bedtime due to potential drowsiness and dizziness 3
• Some women may experience difficulty swallowing progesterone capsules; take with a glass of water while standing 3
• Vaginal progesterone has better bioavailability for uterine effects with fewer systemic side effects 7

Monitoring

• Initial evaluation at 3-6 months after starting therapy
• Annual clinical reviews thereafter
• Report any persistent or recurrent abnormal vaginal bleeding 2
• For pregnancy applications, monitor cervical length and signs of preterm labor

Progesterone therapy is a critical intervention for specific reproductive health conditions, with dosage and administration route varying by indication. The evidence strongly supports its use for preterm birth prevention in high-risk women and for endometrial protection in those taking estrogen therapy, with specific regimens established for each indication.