Prenatal Ultrasound and X-ray - Potentially Adverse Effects on the CNS

Abstract: The aim with this thesis was to assess the impact of prenatal ultrasound exposure on psychotic illness, childhood brain tumors (CBT) and school achievement, and to evaluate prenatal X-ray exposure and the risk of CBT.In a cohort study, children born in Malmö 1973-1978, where prenatal ultrasound was used routinely, were considered exposed (n=13, 212) and children born at hospitals with no use of ultrasound, were considered unexposed (n=357,733). Exposed men had a tendency toward a higher risk of schizophrenia. For other psychoses there were no differences between groups. Other factors related to place of birth might have influenced the results. In a case control study, children born 1975-1984 with a diagnosis of CBT (n=512), and randomly selected control children (n=524) were included. Exposure data on X-ray and ultrasound from antenatal records was completed with information from the Medical Birth Register. We found no overall increased risk for CBT after prenatal X-ray exposure. When stratifying by histological subgroups, primitive neuroectodermal tumors had the highest risk estimates. For ultrasound exposure, no increased risk for CBT was seen and numbers of examinations or gestational age at exposure had no substantial impact on the results. In a follow-up of a randomized trial on prenatal ultrasound scanning 1985-87, we assessed the children’s school grades when graduating from primary school (15-16 years of age). We performed analyses according to randomization, ultrasound exposure in the second trimester and exposure at any time during pregnancy. There were no differences in school performance for boys or girls according to randomization or exposure in the second trimester. Boys exposed to ultrasound any time during fetal life had a reduced mean score in physical education and small, non-significant increased risk of poor school performance in general.