Impedance Cardiography to Decrease the Risk of Preeclampsia

To determine if the use of impedance cardiography can identify appropriate medications for use in treating chronic hypertensive patients to decrease the risk of preeclampsia.

Impedance cardiography helps determine whether vasoconstriction or an elevated cardiac output is occurring. The test is easy to perform and non invasive. The treatment for an elevated cardiac output in pregnancy is a beta-blocker while a vasodilator is used for vasoconstriction. If a beta-blocker is given to someone that vasoconstricted, this might make the cardiovascular parameters worse, leading to no improvement in future pregnancy issues. Likewise, if a vasoconstricting drug is given to someone with an elevated cardiac output, it could potentially make the cardiovascular parameters worse. All centers in the United States that choose to prescribe an antihypertensive medication for use in pregnancy do so by trial and error, whereas impedance cardiography can help the clinician choose the best medication from the start. Many pregnant patient patients have chronic hypertension and this population is at increased risk for superimposed preeclampsia and other pregnancy complications. The current recommendation for pregnancy is to NOT treat mild hypertension because studies have not shown any benefit. These studies, have also not shown any harm. Prior studies that have shown no benefit to treatment of mild hypertension in pregnancy may be hampered by choosing the wrong antihypertensive medication, thereby not improving the rate of superimposed preeclampsia and other pregnancy related complications.

Treatment arm patients will be randomized to treatment with antihypertensive medications used with pregnancy for thirty years. Intervention: Labetalol Hydrocholoride 200 mg orally every 12 hours Nifedipine 60 mg orally daily Atenolol 25 mg daily

Non treatment Arm patients who are randomized to the non-treatment arm will not receive antihypertensive medications.

Anti-hypertensive medication prescribed for increased systemic vascular resistance as determined by impedance cardiography

Anti-hypertensive prescribed for increased cardiac output with tachycardia or maternal pulse rate 110 or greater

Inclusion Criteria: Pregnant patients 18-51 years old Less than 20 weeks gestation with mild chronic hypertension - Not on antihypertensive medications Exclusion Criteria: Patients with an allergy to antihypertensive medication or contraindication for their usage such as certain cardiac or neurologic disorder during pregnancy Patients who have a blood pressure 140/90 or greater -