Part#1: 15 healthy volunteers; 2 assessment sessions. Session 1: StO2 vs. EndoPAT Method comparison analysis; both StO2 and EndoPAT will be applied simultaneously & pulse oximeter probes placed bilaterally on fingers. Baseline readings will be taken for 5 minutes. The blood pressure cuff will be inflated to suprasystolic pressure and StO2 and pulsatile volume changes will be measured by peripheral arterial tonometry, continuous measurement for 3 min and repeated every 10 minutes for 3 sessions.

Session 2: This session will occur within 1 week of session 1. This session is to determine the consistency of the response.

All probes will be applied as in session 1 and cycles of 10 minutes for 3 sessions will be done. All the measurements in session 1 will be captured in session 2.

This will determine inter-day variability. (total time is 53 min).

Part #2: 20 participants, 10 normotensive and 10 pre-eclamptic pregnant women during their visit to labor floor.

Session 1: Both StO2 and EndoPAT will be applied simultaneously to the same arm below a BP cuff. Baseline readings will be taken for 5 minutes, the blood pressure cuff will be inflated to suprasystolic pressure StO2 and pulsatile volume changes will be measured by peripheral arterial tonometry, continuous measurement for 3 min and repeated every 10 minutes for 3 sessions.

Additionally, vascular stiffness with be measured by SphygmoCor to measure pulse wave velocity (PWV).

Participants must also agree to participate OB/GYN biobanking protocol HIC# 1601017004 to be in this study.

All participants will have follow-up at 48 hours, including a blood draw, assessment of endothelial function and vascular stiffness.

Part #2: 20 participants, 10 normotensive and 10 pre-eclamptic pregnant women during their visit to labor floor.

Session 1: Both StO2 and EndoPAT will be applied simultaneously to the same arm below a BP cuff. Baseline readings will be taken for 5 minutes, the blood pressure cuff will be inflated to suprasystolic pressure StO2 and pulsatile volume changes will be measured by peripheral arterial tonometry, continuous measurement for 3 min and repeated every 10 minutes for 3 sessions.

Additionally, vascular stiffness with be measured by SphygmoCor to measure pulse wave velocity (PWV).

Participants must also agree to participate OB/GYN biobanking protocol HIC# 1601017004 to be in this study.

All participants will have follow-up at 48 hours, including a blood draw, assessment of endothelial function and vascular stiffness.

Participants with hypertension will be followed in conjunction with routine clinical follow-up at 2, 6 and 12 weeks post-partum.

• StO2 probe is a lightweight plastic probe that will be applied over the brachioradilalis muscle (anterolatereal aspect of the forearm) where there is less subcutaneous fat and taped in place.
• The EndoPAT probe will be place on a finger on the same arm.
• Pulse oximeter probes will be connected to a finger on each hand.

Measurement of forearm StO2 during routine cycling of a blood pressure cuff can provide a continuous index of endothelial functional reserve. Baseline measures are collected in healthy and pregnant participants.

Measurement of forearm StO2 during routine cycling of a blood pressure cuff can provide a continuous index of endothelial functional reserve. This will only be measured in pregnant participants.

Measurement of Endopat during routine cycling of a blood pressure cuff can provide a continuous index of endothelial functional reserve. Baseline measures are collected in healthy and pregnant participants.

Measurement of Endopat during routine cycling of a blood pressure cuff can provide a continuous index of endothelial functional reserve. This will only be measured in pregnant participants.

SphygmoCor is a measurement of vascular stiffness. This will only be measured in pregnant participants.

SphygmoCor is a measurement of vascular stiffness. Baseline measures are collected in healthy and pregnant participants.

Measurement of forearm StO2 during routine cycling of a blood pressure cuff can provide a continuous index of endothelial functional reserve. This will only be measured in hypertensive pregnant participants.