Variations from morning to afternoon of middle cerebral and umbilical artery blood flow, and fetal heart rate variability, and fetal characteristics in the normally developing fetus.

In normal pregnancies, variations in fetal cerebral and umbilical blood flow parameters were observed between AM and PM independent of other fetal movements or baseline fetal heart rate. In contrast, uterine flow parameters remained stable across the day. These findings may have implications for the use of serial Doppler parameters used to guide clinical management in high-risk pregnancies.