This is an observational study comparing microcirculation of pregnant to non-pregnant women. "Microcirculation" means blood flow to the extremely small blood vessels in one's body. During pregnancy the amount of blood in a woman's body increases. The body responds to this increase by pumping more blood through the heart and narrowing the size of blood vessels.

There are many types of blood vessels that have different roles in the body. Larger blood vessels. Transport blood to and from body organs like the brain and liver. Small vessels (microcirculation)distributes blood to the organ tissues. The microcirculation can change blood flow and blood pressure. Microcirculation is involved in delivering oxygen and nutrients to your body, removing waste products, and regulating body temperature.

The investigators current understanding of the microcirculation in pregnant women is limited. There is a device available that can measure microcirculation. It is known as Sidestream Dark Field (SDF) imaging. It is a special type of camera that captures pictures of the microcirculation. In this study the investigators will compare the microcirculation, as seen with SDF imaging, of pregnant women to non-pregnant women. By improving the investigators understanding of maternal microcirculation the investigators are adding to the knowledge of how the pregnant body works. The investigators hope to then translate this knowledge into further studies to improve maternal and fetal outcomes through prevention and treatment of maternal low blood pressure caused by spinal anesthesia.

The objectives of this observational trial are; to compare the sublingual microcirculation of pregnant subjects to that of comparable non-pregnant volunteers; to evaluate the usefulness of a non-invasive technology, SDF imaging in pregnant and non-pregnant subjects.

By improving our understanding of maternal microcirculation we not only add to the knowledge of maternal physiology, we hope to then translate this knowledge into further studies to improve maternal and fetal clinical outcomes through prevention and treatment of maternal hypotension especially in relation to spinal anesthesia.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) Physical Status I-II (ASA I Healthy, ASA II - mild and controlled systemic disease)
• Pregnant: singleton, 36 - 40 weeks EGA, non-labouring
• Non- Pregnant - Healthy female volunteers who have never been pregnant, matched to pregnant patients for age ± 1 year

Exclusion Criteria:

• Obesity (BMI > 35 kg/m2)
• Hypertensive disease (Essential, gestational, or preeclampsia)
• Diabetes Mellitus Type 1
• Cardiovascular disease
• Smoker (1 cigarette or other tobacco product within 12 months)
• Caffeinated (i.e. coffee, tea, energy drink) beverage with 2 hours

Pregnant group - women with uncomplicated, singleton, at 36 - 40 weeks gestation, non-laboring

Non-Pregnant group - healthy nulliparous female volunteers, matched to pregnant patients for age ± 1 year