Cerebral palsy and severe educational subnormality in low-birthweight children: a comparison of births in 1951-53 and 1970-73.

The prevalence at school age of cerebral palsy and severe education subnormality in children of low birthweight (less than or equal to 4 lb=1814 g) born to residents in the region served by the South East Thames Regional Health Authority in the early 1970s was compared with that in children of the same birthweight born in 1950-53. The prevalence of one or both of these defects was lower in the 1970s cohort; this was due to both a fall in the incidence of extreme gestational immaturity among children of low birthweight and a reduction in risk of defects to the gestationally immature births that occurred. The decreased risk of these defects in children of low birthweight was approximately counter-balanced by the increased likelihood of their survival; among children of all birthweights the prevalence of these defects attributable to children of very low birthweight changed little.