[Fetal cerebral and renal circulation--a longitudinal study in the 2d half of pregnancy].

In a prospective longitudinal study 34 women were subjected to the following investigations 4-weekly from the 23rd to the 41st week of pregnancy: Doppler sonography of the umbilical artery, arteria cerebri media (ACM) and arteria renalis (AR), fetal biometry, estimation of the amniotic fluid volume and cardiotocography (CTG). 30 pregnancies ended in the birth of normal weight babies with no perinatal problems and in 108 examinations blood flow velocity waveforms of high quality were recorded in each vessel. We calculated the pulsatility index (PI), which was always within the normal range for the umbilical artery. Regression analysis was used to derive the 90% confidence intervals for the PI of ACM and AR and the PI ratio AR/ACM. A linear relationship was found between the AR PI and gestational age, while the relationship between the ACM PI and gestational age is better described by a quadratic equation. In both vessels a fall in PI was observed with advancing gestation. In the renal artery waveforms with absence of end-diastolic flow velocities were recorded up to 34 weeks only. CTG was assessed by the Fischer score, which showed a highly significant, positive correlation with gestational age (r = 0.316), but no correlation with the PI of the middle cerebral artery. The amniotic fluid volume showed a negative correlation with gestational age (r = -0.19), but no correlation with the PI of the renal artery.