The parenteral drugs include intravenous injection of abetalol, hydralazine and calcium antagonists. Methyldopa 250 mg twice daily can be increased up to maximal 4 gram daily. Labetalol can be given 100 mg twice daily and maximum 400 mg daily. Atenolol, a beta blocker, which no effect of alpha blocker is associated with reduced placental and fetal blood flow during the birth when it is given starting from the early pregnancy.