Birth weight and school-age disabilities: a population-based study.

Mortality rates have declined for low birth weight and extremely low birth weight infants. Yet, the consequences of survival for these children may be adverse developmental outcomes. Few studies to date have examined school-age outcomes for these children. The participants in this study represented a population-based cohort of Florida children who were born between 1982 and 1984 and who were receiving a public school education in 1996-1997. Linkage methodology was used to establish a cohort of 267,213 children aged 12-15 years with both birth certificate and school records. Birth weights were stratified into 500-g increments beginning with <or=999 g; 17% of the population had some school-identified disability. Risk ratios for specified school-identified disabilities increased as birth weight decreased for all birth weight strata of <or=3,499 g. Narrow increments of birth weights may better portray a more accurate estimate of risk for infants born at extremes than the conventional definition of <2,500 g.