Evaluation of Compensatory Reserve in Obstetrical Patients

The Investigators hypothesize that the Compensatory Reserve Index (CRI) algorithm will help to guide fluid management in women undergoing regional anesthesia, giving birth, and/or undergoing maternal fetal intervention surgery. Specific aims: Collect noninvasive physiological waveform data from patients undergoing regional anesthesia and either fetal intervention surgery or labor and delivery at Children's Hospital Colorado in order to: 1. Determine how regional anesthesia influences CRI algorithm calculations 2. Determine if the CRI algorithm is able to detect changes in central volume status associated with fetal surgery. 3. Determine if the CRI algorithm is able to detect changes in central volume status associated with labor and childbirth specifically at the time of delivery, when most women experience some amount of bleeding. 4. Examine CRI associated with induction of regional anesthesia and determine if there is a minimal CRI below which one can expect hypotension and if there is a trend down in CRI following induction of regional anesthesia that could anticipate/predict hypotension. 5. Determine if there is a correlation between fetal heart rate abnormalities and CRI. 6. Examine CRI associated with fetal monitoring.