Oral Progesterone for Prevention of Preterm Birth

Prevention of Recurrent Preterm Birth With Micronized Progesterone

To evaluate whether daily oral micronized progesterone is effective in preventing recurrent spontaneous preterm birth (RSPB) and whether micronized progesterone use increases maternal serum progesterone levels.

To evaluate whether 400 mg daily oral micronized progesterone from 16 to 34 weeks' is effective in preventing recurrent spontaneous preterm birth (RSPB) and whether micronized progesterone use increases maternal serum progesterone levels.

Inclusion Criteria:

• pregnant women less than 20 weeks' gestation who had at least one prior spontaneous preterm birth of a liveborn baby between 20 & 0/7 weeks' and 36 & 6/7 weeks' gestation.

Exclusion Criteria:

• multiple gestations, the presence of major fetal anomalies, progesterone use in the current pregnancy (ongoing or past), the presence of a cervical cerclage, and the presence of a placenta previa.