Doppler ultrasound provides information on the different aspects of blood flow, such as flux, direction, speed, volume, and impedance. The aim of the present study is to find the effects and the reference ranges of hypertension on blood flow of pregnant women. The study was conducted on 117 pregnant women. The data recorded via routine Doppler measurements at 14-40 weeks of gestation. The study group was divided into two groups: healthy pregnant in category (1) and pregnant with hypertension in category (2). A strong negative correlation was between gestational age (GA) and the resistive index of the middle cerebral artery (MCA-RI) from the 14th to the 28th weeks. A strong positive correlation was between MCA (Pulsatility index (PI) and RI), and was between umbilical artery UmA (RI and PI) with gestation period in both groups. A negative linear correlation was between peak systolic velocity (PSV) and RI. The parameters measured of hypertension showed that they have effects on blood flow and can be considered as the reference ranges of hypertension for blood flow of pregnant women.