A GROUP of papers in this issue summarize new and very interesting advances in the treatment of erythroblastosis fetalis and in our understanding of the pathophysiological processes which lead to death from this condition. They also mark a new technical feat; for the first time it has been possible to treat, and to treat successfully, the human infant in utero for a hitherto fatal condition. It is interesting to follow the processes by which these advances in knowledge have developed, and to survey the wealth of new information on many different problems which has accrued.
Diagnosis precedes treatment, and the first need was to obtain a better forecast of the rate of development of the disease in Rh-isoimmunized pregnancies than the maternal antibody titer.