Patient description: 19 yo Hispanic female G1P1 at 32+ 6 weeks of gestational age presented to the OB clinic for routine follow up complaining of mild headache and leg swelling. Primary evaluation revealed BP of 146/99 and urine dipstick with 3+ proteins. Her BP and U/A were normal in previous visit. Repeat BP a few hours later is 150/100 mmHg. Laboratory studies showed a normal hematocrit, platelet count, and liver transaminase levels. She is complaining of fatigue but no fever or chills. She is also suffering of headaches with no vision changes. No shortness of breath, cough, chest pain, orthopnea and palpitations or skin rash were observed. Her physical exam was negative for abdominal pain, change in bowel habits, nausea, vomiting, dysuria, frequency, hematuria or frothy urine. Leg swelling was observed with no arthralgia or back pain. She has no specific past medical issues and only uses prenatal vitamins. Her family history is positive for DM type 2 and HTN. She is a social alcohol consumer with the negative history of smoking or drug use. She is only have one partner in past 2 years and didn't have any contraceptive methods since 2 years ago. Her BMI was 24 at the first

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Pulmonary Hypertension Males or females, 18 years of age or older Diagnosis of sickle cell disease (electrophoretic documentation of SS, SC, or S thalassemia genotype is required) or thalassemia For female subjects, on a reliable method of birth control or not physically able to bear children. <TAB> For Stage II Mild to severe pulmonary hypertension with mean pulmonary artery pressure greater than 25 mm Hg at rest or greater than 30 mm Hg during exercise, measured by pulmonary artery catheterization Pulmonary artery wedge pressure or left ventricular end-diastolic pressure less than or equal to 18 mm Hg or gradient between pulmonary artery diastolic pressure and wedge pressure greater than 8 mm Hg or echocardiographic to left ventricular dysfunction For female subjects, on a reliable method of birth control or not physically able to bear children. For Stage III Mild to severe pulmonary hypertension with mean pulmonary artery pressure greater than 25 mm Hg at rest or greater than 30 mm Hg during exercise, measured by pulmonary artery catheterization in patients on chronic sildenafil therapy for at least three months. Patients receiving combination drug therapy with other drugs (e.g., endothelin antagonists, prostacyclins) are allowed to participate in stage III as long as sildenafil is one of the components of the combination regimen Pulmonary artery wedge pressure or left ventricular end-diastolic pressure less than or equal to 18 mm Hg or gradient between pulmonary artery diastolic pressure and wedge pressure greater than 8 mm Hg or echocardiographic to left ventricular dysfunction Must be on chronic sildenafil therapy on a stable dose for at least three months For female subjects, on a reliable method of birth control or not physically able to bear children  For Stage I Current pregnancy or lactation Any condition that in the opinion of the study investigators would adversely affect the outcome of the study or the safety of the volunteer. For Stage II and III Current pregnancy or lactation Any of the following medical conditions 1. Stroke within the last six weeks. 2. History of sustained priapism requiring medical or surgical treatment, unless currently impotent or on exchange transfusion therapy, within two years