Preterm Birth Prevention with Progesterone

Primary Recommendations

• The American College of Obstetricians and Gynecologists recommends oral progesterone 400 mg daily for preventing preterm birth in singleton pregnancies, though vaginal progesterone is the preferred route based on stronger evidence for preterm birth prevention 1, 2

Specific Clinical Indications

• For singleton pregnancies with short cervical length (≤20 mm) at 18-24 weeks, the American College of Obstetricians and Gynecologists suggests that oral progesterone 400 mg daily can be used, though vaginal administration has more robust evidence 2
• Women with prior spontaneous preterm birth should receive 17-alpha-hydroxyprogesterone caproate (17P) 250 mg IM weekly instead, as this is the recommended first-line therapy for this population 3, 4

Key Clinical Distinctions by Population

• For singleton pregnancy without prior preterm birth, vaginal progesterone is preferred (90-mg gel or 200-mg suppository daily) 1, 5
• For singleton pregnancy with prior spontaneous preterm birth, 17P 250 mg IM weekly is the recommended therapy, starting at 16-20 weeks and continuing until 36 weeks 3, 4

Populations Where Oral Progesterone Should NOT Be Used

• The American College of Obstetricians and Gynecologists recommends avoiding oral progesterone in active preterm labor, preterm premature rupture of membranes, twin or triplet pregnancies, and women with prior preterm birth as primary prevention 1, 3, 6

Safety Considerations

• Long-term follow-up studies show no adverse effects on child development, physical examination, or performance, and no short-term safety concerns have been identified in large trials 1
• Progesterone exposure, even in first trimester, has not shown long-term fetal harm 1