A CLINICAL impression that poliomyelitis occurs with undue frequency during pregnancy and its possible importance in relation to susceptibility have been emphasized in previous papers.1234 There are many reports of cases in the literature that deal with various aspects of the disease in the pregnant mother, such as effects of the disease on the mother and the fetus or obstetric problems created by the occurrence of the disease. Few reports have dealt specifically with the question of frequency of the disease in pregnancy or its significance. Within the age groups concerned pregnancy is relatively frequent and poliomyelitis is infrequent. For . . .