Growth velocity of some fetal parameters. I. Brain weight and brain dimensions.

In this study, fetal growth velocities of the brain weight (whole brain and infratentorial part) and of the right and left fronto-occipital diameters were established from 420 normal fetuses and neonates. The age of the subjects ranged from 10 to 41 gestational weeks. Growth rates were computed by time intervals, and velocity curves were plotted with their 95% confidence intervals. The whole brain displays an accelerating pattern of growth until 35 weeks; thereafter, the growth rate breaks down. The growth velocity of the infratentorial part of the brain increases throughout fetal life, without a fall at 35 weeks. Moreover, it grows faster than the whole brain after 24 weeks. The lengths of the hemispheres present a steady decreasing pattern of growth velocity throughout pregnancy.