Objectives: Preeclampsia is a high prevalence complication in pregnancy and is responsible for 36% of maternal mortality worldwide. The offspring of mothers with preeclampsia face many problems after birth and in their lifetime. The fetal renal is one of the most vulnerable organs following maternal preeclampsia. In this regard, the present study investigated the relationship between the severity of preeclampsia and fetal renal artery resistance and pulsatility.

Materials and Methods: In general, 91 pregnant women were included and divided into control and preeclampsia groups. The control group included 43 women with normal pregnancy and the preeclampsia group consisted of 48 pregnant women who suffered from preeclampsia and were classified into patients in severe and non-severe preeclampsia groups each containing 24 cases. Renal artery Doppler ultrasound was performed, and then the systole/diastole ratio (S/D), pulsatility index (PI), and resistance index (RI) were measured as well.

Results: The S/D ratio, RI, and PI significantly decreased in the preeclampsia group (P<0.001) compared to the control group. The S/D ratio in severe preeclampsia was significantly lower in comparison with non-severe preeclampsia (P<0.001). Finally, the amniotic fluid index was related to the PI (P<0.05), and severe preeclampsia significantly increased the pregnancy termination before 34 weeks (P<0.001).

Conclusions: Preeclampsia deceased the resistance of renal arteries by altering the fetal renal blood flow. These changes can intensify in patients with severe preeclampsia compared to non-severe preeclampsia.