Changes in cerebral hemodynamics after week 32 of gestation in fetuses with late-onset fetal growth restriction

BACKGROUND: Late-onset fetal growth restriction is characterized by changes in fetal cerebral hemodynamic patterns. Blood flow parameters in the anterior, middle, and posterior cerebral arteries have been studied previously, and there was shown a relationship between changes in certain cerebral artery vascular resistance parameters and increased risk of adverse perinatal outcomes such as fetal hypoxia in labor, cesarean section, and stillbirth. AIM: The aim of this study was to search for cerebral hemodynamic patterns in fetuses with late-onset fetal growth restriction after week 32 of gestation. MATERIALS AND METHODS: This prospective study included 110 pregnant women at week 32 or more of gestation who underwent fetal ultrasound (fetometry and Doppler with additional measurement of vascular resistance parameters in the anterior and posterior cerebral arteries). Ultrasound findings were assessed for the presence of late-onset fetal growth restriction. The systole-diastolic ratio, resistance index, and pulsatility index were evaluated in appropriate-for-gestational-age fetuses and in fetuses with late-onset fetal growth restriction. RESULTS: A total of 128 middle, 86 anterior, and 87 posterior cerebral arteries measurements were included in the calculations. From weeks 32–33 to preterm gestation in appropriate-for-gestational-age fetuses, a decrease in the middle cerebral artery parameters was observed, while in the anterior and posterior cerebral arteries, the vascular resistance parameters remained at the same level or slightly increased. A nonlinear trend of blood flow changes in the anterior and posterior cerebral arteries was observed in fetuses with fetal growth restriction — the values increased by weeks 34–36 of gestation and decreased in preterm gestation. At the same time, differences (р 0.05) were found between the median values of the systolic-diastolic ratio, resistance index and pulsatility index in the anterior and posterior cerebral arteries at weeks 34–36 and those at preterm gestation. CONCLUSIONS: Changes in fetal cerebral hemodynamics in fetal growth restriction, in particular, a shift in the peak values of vascular resistance parameters to later gestational periods may be associated with changes in the development of integrative functions of the central nervous system and neurovascular development of the fetal brain (cortex), which occurs predominantly in the third trimester of pregnancy.