The investigators previously demonstrated that epidural ropivacaine reduces uterine artery vascular resistance in a dose dependent manner in pre-eclampsia. The investigators also noted a marked right-left difference in vascular resistance between paired uterine arteries, which was almost completely abolished following epidural ropivacaine. However, this novel observation was not a stated outcome variable before the study began. This study assesses right-left difference in vascular resistance between paired uterine arteries as a primary end-point, assesses the dose-response effect of epidural lidocaine and compares the effect observed in pre-eclampsia with that in two control populations (term normal pregnancy and non-pregnant controls).

Inclusion Criteria:

• Pre-eclampsia patients and normal pregnancy controls scheduled to receive epidural catheterization for induction of labor or Cesarean delivery. Non-pregnant controls receiving epidural catheterization for elective surgery. Pre-eclampsia group:

  1. gestational age between 35 to 40 completed weeks
  2. uterine artery notching OR evidence of reduced uterine artery blood flow
  3. resting systolic pressure > 140mmHg or diastolic pressure > 90mmHg measured twice at least 6 hours apart
  4. proteinuria (at least 0•1 g/l in two random samples at least 6 hours apart or at least 0•3g in a 24 hour collection).

• Normal pregnancy control group:

  1. gestational age between 35 to 40 completed weeks
  2. absence of other inclusion factors for the pre-eclampsia group. Non-pregnant control group: Non-pregnant women of reproductive age.

Exclusion Criteria:

• Active labor, resting blood pressure ≥ 160/110 (recorded on at least two occasions 6 hours apart), coagulopathy or other contraindications for epidural catheterization, abnormal fetal heart tracing, known fetal anomaly, intrauterine infection, placental anomalies, twins, and refusal of consent.