Objective: This study was done to assess the relationship between blood viscosity in normal pregnancies and those complicated with preeclampsia and FGR. Methods: A case-control study involving 60 women with FGR, and 354 uncomplicated women. The FGR group was further subdivided into normotensive and hypertensive women. The blood sampling obtained just before delivery. We compared the maternal blood viscosity and umbilical cord blood viscosity between the three groups. Results: Age, BMI, and maternal weight were comparable in the groups, while gestational age at delivery as well as fetal outcome parameter were statistically significant unfavourable in patients with hypertensive FGR. The mean of the systolic viscosity in women with hypertensive FGR was significantly greater than those with normotensive FGR and uncomplicated women ( 4.696 (±1.044) mP vs4.220 (±0.704)mP, 4.350(±0.824)mP, respectively, p=0.007). The mean oxygen delivery index in women with hypertensive FGR was significantly lower than other 2 group. (8.309(±1.312) vs 8.537(±1.399) vs 8.779(±1.0438), respectively, p=0.045). Conclusion: Increased blood viscosity may be associated with the hypertensive FGR. However, further validation of these findings with more robust multicenter prospective and longitudinal characterization of blood rheology in pregnancy should be carried out.