Members of the Department of Obstetrics at King’s College Hospital, London SE5 have measured the umbilical venous oxygen and carbon dioxide tensions, pH, lactate and glucose concentrations, nucleated red cell (erythroblast) content, and haemoglobin concentration in 38 fetuses with intra-uterine growth retardation in which blood sampling was performed by cordocentesis. The oxygen tension was below the normal mean for gestational age in 33 cases (87%). The severity of fetal hypoxia correlated significantly with fetal hypercapnia , acidosis, hyperlacticaemia, hypoglycaemia, and erythroblastosis. The authors conclude that signs of asphyxia at birth are not necessarily due to the process of birth but may originate before birth. 
COMMENT: Law courts often assume that any infant who develops cerebral palsy must have been damaged by obstetric mismanagement. This study demonstrates that what happens before delivery is sometimes more important than what happens during and after the birth process. Cordocentesis is attended by technical risks and cannot be used routinely. There is need for a non-invasive and repetitive test for the prenatal diagnosis of fetal hypoxia.