Birth-weight ratio and cerebral palsy.

The birth-weight ratio, a convenient measure of fetal growth, has been used to assess the importance of antecedent and perinatal factors in a retrospective analysis of 605 cases of congenital cerebral palsy. All had been seen by the author at a special clinic over a period of three decades. The ratio (normally 1) is high in the very premature, falls in the middle of the third trimester, then begins to rise again at term. Abnormalities of pregnancy, or a history of maternal pregnancy-losses, depress the ratio perceptibly. In both singletons and twins, there is no significant relationship between a low ratio and the severity of the clinical condition, and presumably the extent of the brain damage. The findings suggest that growth retardation is an association and not a cause of perinatal vascular-anoxic lesions.