A longitudinal study of fetal growth variability.

The aim of this study was to assess the variability in individual fetal growth rhythms in comparison to averaged standard curves obtained from cross-sectional data. Biparietal diameter (BDP), abdominal transverse diameter (ATD) and femur length (FL) were measured by ultrasonography in 24 normal subjects, and the variance in growth rates determined for four time intervals: 12-26, 26-34, 34-37 and 37-39 weeks gestation. BPD, ATD and FL growths were always linear until 26 weeks with low variances in growth rates. Growth rates decreased thereafter whereas related variances increased significantly with a great diversity in individual growth trajectories. This study questions the relevance of mathematically smoothed curves which lead to an erroneous impression of growth trajectory uniformity when ultrasonography does not seem to be able to predict accurately newborn biometrical characteristics by the end of gestation. Copyright 2000 S. Karger AG, Basel