Prenatal and perinatal factors in childhood cancer.

The material consists of malignant tumours in childhood notified to the Finnish Cancer Registry in 1959-1968. The maternity health centre cards for these children were collected through the National Board of Health. The immediately preceding parturient of the same maternity health centre was selected as the control. The number of complete pairs obtained for the final analysis was 972. All data concerning the parents, the pregnancy, parturition and the child were extracted from the cards. Information on the cancer patient and the paired control was compared. The results are presented as a comparison of the total tumour series and the controls, but also in smaller sub-groups: leukaemias (373 cases), brain tumours (245 cases) and other tumours (354 cases). Other tumours are further divided into: kidney tumours (96), eye tumours (37) and bone tumours (56). No significant correlations were found between potential aetiologic factors and the cases of cancer. The risk ratio for leukaemia in the group with pelvic radiography was 1.9, and in the group given vaccination against polio 1.8. However, because of the rare occurrence of the exposure mentioned these groups were small and the increase in the risk ratio statistically insignificant. BCG vaccination of children was common (90%) and no differences were established between the tumour and the control groups in this respect.