To evaluate the maternal blood concentrations of brain natriuretic peptide (BNP) during the second and third trimesters of a normal pregnancy. We will attempt to define a normal range for pregnancy and any outliers that may serve as markers for abnormal cardiovascular physiology.

The brain natriuretic peptide (BNP) is a useful marker for volume overload, increased filling pressures and stretching of the myocardium. The current literature contains limited and unreliable information regarding normal BNP values in pregnancy. After baseline echocardiogram to detect individuals with asymptomatic structural defects, the participants will submit to 3 blood draws during the second and third trimester and at delivery to determine normal pregnancy values.

Inclusion Criteria:

• women age 18 to 40
• second trimester of pregnancy

Exclusion Criteria:

• known cardiac or valvular disease,
• atrial fibrillation or other arrhythmia,
• pulmonary hypertension,
• chronic hypertension,
• hypertensive disorders of pregnancy,
• morbid obesity (BMI > 40 kg/meter squared)
• history of sleep apnea
• multiple gestation
• known renal dysfunction
• medications known to affect cardiac function
• current or past abnormal echocardiogram

Healthy pregnant women, 18-40