Learning disability and cerebral palsy are often related to factors present before birth. We report three patients (two with schizencephaly, one with unilateral cerebellar agenesis) in whom the timing of an insult to the foetus was known. In the first case, the mother had a trauma at 16 weeks of pregnancy and schizencephaly was discovered in the male infant associated with a left hemiplegia. In the second child, amniocentesis performed at 16 weeks into pregnancy may have been responsible for the same cortical anomaly. In the third case, sequential foetal echographies clearly demonstrated that an apparent unilateral cerebellar agenesis was related to an haemorrhagic event secondary to cerebellar trauma that occurred at 19 weeks of pregnancy. It is suggested that these brain malformations are related to an ischemic mechanism or a traumatic event in foetal life.