Patterns of illness in an infant population in a poor socio-economic status multi-ethnic municipality.

The prevalence and patterns of illness and behavioural disturbances in a birth cohort of 273 infants followed longitudinally are reported. Four percent of infants showed serious morbidity, due to congenital abnormality, chronic illness or gross psychosocial disturbance in the family. Episodic and continuing or recurrent illness was common, but caused little serious morbidity and did not impair growth. Behavioural disturbances manifested by feeding, crying and sleeping difficulties were also common, 22% of all infants being moderately affected and 13% severely affected. Mothers were more concerned by these disturbances than by organic illness. The findings of illness in infants in this study were similar to those of a recent New Zealand study but differ from older overseas studies in which serious infective illness with high mortality was much more common. It is probable that these differences are largely explained by improvement in living conditions.