This study is designed to determine the ED90 for a single dose of phenylephrine for the
treatment of spinal induced hypotension in parturients presenting for an elective CD. The
ED90 is the effective dose at which 90% of subjects will have a "positive" response to
phenylephrine. The primary outcome measure is the ED90 for bolus phenylephrine. Secondary
outcomes include the need for additional vasopressors, glycopyrolate to treat bradycardia,
and the presence of hypertension following administration of phenylephrine.