Many papers showed that the pulsatility index of the fetal middle cerebral artery decreases during gestation. We observed equalization of the PI in MCA and PI in UMB in the perinatal period (after 38 weeks of gestation). We observed the increase the diastolic cerebral flow through the brain in cases of hypoxia. We interpreted that situation as a vasomotor response to fetal hypoxia (for example in IUGR). This phenomenon, is called in the literature as brain sparing effect. The aim of our study was estimation of application Doppler technique in diagnosis of changes in circulatory system in pregnancies complicated by intrauterine growth restriction (IUGR). We included 66 fetuses with IUGR and sonographic signs of the brain sparing effects, without any congenital malformation, oedema and genetic abnormalities to the study group. We included 1730 foetuses from normal, physiological pregnancies to the control group. In all cases time of gestation were calculated from Naegele's rule and were confirmed in sonographic examination before 16 weeks of gestation. SGA fetuses were defined on the basis of ultrasonographic measurements of BPD, HC, AC, FL and weight below 10th percentile of our reference curve. Sonographic examination were performed on Acuson 128 XP/10 with transducers (2.5 MHz-5 MHz). We performed Doppler examinations in MCA and UMB. Redistribution (brain sparing effect) was diagnosed when CPR (cerebroplacental ratio) was less than 1. We analysed the way and time of delivery and neoanatal follow up. Obtained in advance of researches results made possible expression of following conclusions: 1. Use of Doppler techniques in pregnancies complicated by IUGR makes possible diagnosis of hypoxia that helps in settlement of continuing or ending of pregnancy. 2. Changes in Doppler flows in foetus resoluteness outdistance irregular other values of biophysical methods of foetus monitoring.