lower than expected enrollment

Preterm delivery is the most common cause of infant morbidity and mortality in the United States. Some women have episodes of preterm labor during their pregnancy which can be temporarily stopped. These women, however, are at high risk for delivering before term. At this time, we do not have sufficient evidence to use any medication to help prevent these women from delivering early. Recently, preliminary studies have shown that progesterone may help prevent some women at high risk for preterm delivery from delivering early. Our study will investigate whether progesterone can help this specific group of women, women with arrested preterm labor, deliver healthy infants at term.

The purpose of this study is to test the efficacy of progesterone in prolonging human pregnancies complicated by arrested preterm labor. Animal labor has not been shown to be equivalent to human labor and would not be an appropriate substitute for this study.

In addition, this medication has been previously used in pregnant women without any evidence of significant harm to the mother or fetus. Women will be approached for enrollment in the study during their hospitalization for preterm labor. If they choose to enroll, they will have weekly MD visits at the obstetrical clinic, daily use of vaginal progesterone that will be self administered, and routine obstetric care at the time of recurrent labor and delivery. The daily progesterone is not a part of routine care for these patients. In addition, we will ask patients to fill out a written questionaire one week after starting the medication to describe any subjective symptoms that may be associated with this medication. Finally, we will assess the peripheral levels of progesterone with a blood draw prior to starting the mediation, one week after starting the medication, and at the time of recurrent pre-term labor or delivery. The first two of these blood draws will be in addition to the standard treatment. The final blood draw will involve collecting an extra sample at a time when the participant would normally have blood drawn as a part of routine care.

Inclusion Criteria:1. Pregnant women with arrested preterm labor between 24+0 to 33+6 weeks pregnant.

2. Intact membranes 3. Singleton pregnancy 4. Greater than or equal to 18 years of age 5. Cervical dilation less than or equal to 4cm Exclusion Criteria:1. Any contraindication to on-going pregnancy 2. Placental abruption 3. Placenta previa 4. Lethal fetal anomalies 5. Premature rupture of membranes 6. Multiple gestation 7. Less than 18 years old 8. Known allergy to any component of the study medication or placebo 9. Severe maternal medical illness

Up to 28 days after the delivery.

Very limited enrollment, study terminated early.