Influence of illness on developmental progress in children under two.

Illnesses occurring in children under two were recorded in relation to a systematic programme of child surveillance in one general practice.The most important result of this study was that although illness does have a detectable effect on developmental progress, the degree of that influence is for the most part small.Illnesses experienced between 0 and 7 months have less influence upon seven-month developmental scores than upon 24-month developmental scores, but have a greater influence upon the latter than do illnesses experienced between 7 and 24 months.There was a significantly higher consultation rate for boys and for children from social classes 3b, 4, and 5.