A longitudinal study of numbers of males and females in mental retardation services by age, IQ and placement.

A year-by-year analysis up to age 22 was carried out of the numbers of males and females in a birth cohort receiving mental retardation services in a British city. A slight excess of males was found during childhood, with the largest excess occurring at the upper end of the IQ range, the borderline area for classifying children as mentally retarded. There was also a large male excess found in residential care at each age. During the young adult years, this predominance of males in residential care was offset by an excess of females attending day care centres, leading to almost equality of numbers of males and females receiving some sort of services during this period. Possible explanations for the findings were discussed.