The socio-familial background and prevalence of medical aetiological factors in children attending ESN/M schools.

A study of 169 midly mentally retarded children included consideration of social class, medical risk factors, sibship position, family size and parental education. Ninety-four (56%) children were from social class IV or V. Medical risk factors were identified in 71 (42%) children overall: the prevalence fell from 55% in social class II to 30% in social class V. Prenatal factors were identified in 22 children of whom 14 were third or later born in their sibship: this may reflect increased maternal age at birth. Perinatal events had been reported in 41 children, 20 of whom were in social class III; there was no clear relationship to sibship position. Seven of eight postnatal events had occurred in children in social class II or III. Children in social class IV or V did not appear to be at increased risk of retardation from environmental medical events. Firstborn children were over-represented in the survey, with a minor shift towards fourth-or later-born children. Average family size was 3.25 children (general population 2.0 children). The prevalence of medical risk factors was lowest (18%) in children from large sibships in social class V. Both parents of 86 children had had educational problems: this included 13 children in social class III. Thirty-eight (33%) of these children had medical risk factors, compared with 43/83 (51%) in children where at least one patient had achieved average education. Thirty children had no medical risk factor, nor any history of parental learning difficulty.