Exercise in Pregnancy for Reduction of Blood Pressure in Obese Patients

Hypertension affects 5-10 percent of pregnancies, and complications from hypertensive disorders of pregnancy are the third leading cause of maternal death in the United States. Hypertensive disorders of pregnancy, including preeclampsia, lead to preterm delivery, morbidity and mortality of mother, fetus, and neonate, and are a predictor of development of chronic maternal hypertension, cardiovascular disease, and renal disease. Maternal obesity is increasing dramatically in the patient population, and is an independent risk factor for hypertension and preeclampsia, increasing the risk by two- to four-fold. To date, no effective preventative measure has been found to reduce the risk of preeclampsia or hypertension in high risk pregnant patients. However, observational studies have shown that patients who exercise or who have increased physical activity before and during pregnancy have lower rates of preeclampsia, hypertension, and gestational diabetes. Exercise has been shown in numerous studies to be safe in pregnancy, and is recommended by the American College of Obstetrics and Gynecology as part of routine prenatal care. However, aerobic exercise can be viewed by patients to be difficult to perform during pregnancy, particularly when the patient is obese and at later gestations. Adherence to exercise regimens is therefore low in this patient group. Dynamic resistance training has been shown to lower mean blood pressure both acutely and long term in non-pregnant hypertensive patients, and can be performed more easily by patients with mobility issues. This intervention has not been studied in an obese pregnant population for its effects on blood pressure throughout pregnancy. The long term goal is to develop an intervention that will reduce the barriers to exercise of obese pregnant women that will, in turn, reduce their risk of developing preeclampsia and other hypertensive disorders of pregnancy. The specific objective of this proposal is to study the effect of a structured resistance training exercise intervention on blood pressure in obese pregnant woman, who would be considered high risk for development of hypertensive disorders based on pre-pregnancy BMI. The central hypothesis is that obese pregnant patients who participate in a regular, structured resistance training exercise regimen will have a decrease in mean arterial blood pressure compared to obese pregnant patients who are strongly encouraged to do aerobic exercise (lifestyle intervention) or who participate in routine prenatal care. The investigators formulated this hypothesis, in part, based upon previous studies found in the literature performed in non-pregnant hypertensive patients. The investigators will extrapolate from the experience and methods of the collaborators, who have studied the effects of exercise on gestational diabetes.