Standards for Dysmorphological Diagnosis in Human Fetuses

This study provides new standards for some fetal dimensions frequently concerned with dysmorphological syndromes. Seven dimensions were included: the outer and inner canthal distances (OCD and ICD), the anteroposterior and transversal ocular diameters, the biparietal diameter and head circumference, and the inter-nipple distance. Subjects came from a large data set including more than 4000 fetuses autopsied in fetopathology units of pediatric hospitals in Paris between 1986 and 2001. From this data set, 673 subjects were carefully selected by exclusion of multiple pregnancies, macerated and malformed fetuses, and subjects with abnormal karyotypes and severe infections. Fetal ages ranged from 11 to 42 gestational wk, with a very large sample of fetuses in the first half of gestation. The standards of each dimension were computed in relation to age, as well as the ratio ICD/OCD. The mathematical models used to fit the percentile growth curves were carefully selected for each variable. This study supplies a set of accurate standards of specific dimensions useful for dysmorphological diagnosis in fetuses.