REN and Hypertension: Results from a recent trial, treatment for mild chronic hypertension during pregnancy, underscore the important of blood pressure control in pregnancy for the prevention of adverse outcomes [54], and patients with hypertension in our study were treated with labetalol (a beta blocker) or nifedipine (a calcium channel blocker in the dihydropyridine class), where the former can decrease and the latter can increase plasma renin activity [55], potentially confounding interpretation of RAAS in pregnancy.