Pharmacokinetics of Progesterone in Pregnancy

Prospective study of 6 women with singleton pregnancies 18 0/7- 23 6/7 weeks' gestation with no prior preterm birth or short cervix who are administered a single dose of 200mg vaginal progesterone suppository. Serum progesterone levels will be drawn serially from pre-dose to 24 hours post-dose.

Inclusion criteria

• ≥18 years old pregnant with singleton gestation 16 0/7 - 23 6/7 weeks
• pre-pregnancy BMI 20-40
• no history of prior preterm birth

Exclusion criteria

• history of an adverse reaction to progesterone
• contraindication to progesterone treatment including prior or active thrombus, active hepatic disease, known adverse reaction to progesterone
• medical comorbidity requiring medication including: hypertension, diabetes, substance abuse/methadone maintenance therapy, asthma, thyroid disease
• major fetal anomaly diagnosed on ultrasound or known chromosomal disorder
• multifetal gestation
• vaginal bleeding, preterm labor, premature rupture of membranes, or clinical chorioamnionitis, at the time of enrollment or on Day 1 of study
• any progesterone use of any form previously during the pregnancy
• active vaginitis
• Illicit substance use in pregnancy including cocaine, opiates, marijuana
• abnormal pap smear/+HPV on most recent pap smear
• known or suspected malignancy of the breast or genital organs
• cervical length ≤25mm