The Use of Maternal Serum Unconjugated Estriol for Monitoring the Prevention of Neonatal Respiratory Distress Syndrome

The objective of this project is to evaluate clinical significance of measuring maternal blood estriol levels, after the administration of antenatal corticosteroids to enhance lung maturity. The investigators will test for associations of the change in maternal estriol with the development of respiratory distress syndrome. The investigators are also interested in determining whether salivary estriol is a valid surrogate to estriol blood assays. In addition the investigators will correlate these changes to pharmacokinetic (PK), pharmacodynamics (PD), and pharmacogenetic measures of betamethasone administration and fetal respiratory outcome

We will obtain serum and saliva for estriol measurement before or within 2 hours of antenatal corticosteroid administration and about 24 hours after each dose is given. Women who consent to an optional PK portion of the study will have plasma samples obtained pre-dose and then on a schedule of approximately 0.5-2, 4-8, 10-15, 22-24 hours after the first dose and then 6-8, 24, and 48 hours after the 2nd dose. One sample will be collected in each of these times. A sample of whole blood will be obtained for DNA isolation. At the time of delivery, umbilical cord blood will be collected before being discarded for DNA and plasma. If we are unable to obtain umbilical cord blood, a buccal swab will be collected from the baby for DNA extraction.