ANTHROPOMETRIC MEASUREMENTS IN THE 2ND TRIMESTER FETUS

Normal anthropometric measurements, of accepted value for clinicians a nd pathologists in the assessment of the dysmorphic neonate, have not in the past been available for the second trimester fetus, in which dy smorphic features are often more subtle and objective measurements mos t needed. In order to establish these values 19 anthropometric measure ments, comparable to those published for the larger fetus and neonate, were recorded at autopsy on each of 260 overtly normal non-macerated singleton fetuses between 13 and 26 weeks gestation. Regression lines for each parameter, and growth ratios of potential value for descripti on and assessment of dysmorphic features, were derived. The sex ratio was 1.27 and as there was no statistically significant sex difference for any of the 19 measurements chosen, the data was subsequently poole d. There were linear correlations between gestational age and each gro wth parameter, all but three exceeding 0.90. The linear correlations b etween pairs of growth parameter were higher than the correlations bet ween gestational age and individual growth parameters. This suggests t hat growth parameter pairs, expressed as a ratio, are less affected by errors in gestational age estimation. Ratios enabling the dysmorpholo gist to more objectively assess common observations such as abnormalit ies of head shape, relationship between limb and trunk length and gros s proportional relationships between major body segments were derived. Collected measurements were compared with established ultrasound refe rence ranges. While reference ranges for biparietal diameter and head circumference showed close concordance with those derived from ultraso und measurements, the abdominal circumference was consistently lower t han that measured by ultrasound possibly because of differing trunk po sitions in utero compared with after death. The graphs and ratios deri ved in this study can be rapidly applied to confirm visual impressions at clinical examination and at autopsy.