The antecedents of a population of children with neurodevelopmental di
sability were examined in a sibling-control study: siblings were used
to control for the effect of the family environment on development. Of
294 children with neurodevelopmental disability, 228 who had normally
developing siblings were matched with the sibling of nearest ordinal
position in the family. There was a significantly higher incidence of
prenatal complications among disabled children than among their matche
d siblings, even after correction for gestational age at birth. Prenat
al complications and delayed onset of regular respiration were predict
ive of disability. These data confirm the authors' observation that th
e relation between prenatal complications and neurodevelopmental disab
ility is independent of social class and gestational age at birth.