Defects of the central nervous system in Finland. IV. Associations with diagnostic x-ray examinations.

Based on the Finnish Register of Congenital Malformations a search was undertaken to find possible associations between defects of the CNS and diagnostic x-ray examinations of the mother during pregnancy as well as pelvic x-ray examinations prior to pregnancy. Time-area--matched pregnancies and polydactylic children were used as controls. The risk of having a microcephalic child was increased for mothers with pelvic x-ray prior to pregnancy, but the number of discordant pairs was small. Of the examinations performed during pregnancy, fetal x-ray was significantly more common among mothers who delivered a CNS-defective child. No associations were observed for other kinds of examinations.