A study of time trends in maternal-fetal x-ray exposure.

Abstract

Dales, L. G. (Permanente Medical Group, 3700 Broadway, Oakland, CA 94611), H. K. Ury, G. D. Friedman and W. Eads. A study of time trends in maternal-fetal x-ray exposure. Am J Epidemiol 106:362–369, 1977. The impression that physicians have become more reluctant to expose pregnant women to x-rays and an apparent decline in early childhood leukemia incidence in Alameda County, California, between 1960 and 1969 prompted curiosity as to whether a decrease in in utero diagnostic x-ray exposure had occurred. At the Oakland Kaiser-Permanente Medical Center, where diagnostic x-ray practices were thought to be typical of the county as a whole, utilization of x-rays was ascertained in a sample of pregnant women between 1947 and 1973. For the total sample, no significant change in use of abdominal-pelvic region x-ray films was noted, while among white and black women without major obstetric complications, there was a very small but significant (p < .05) decline over time. Temporal changes in age, race, and parity of subjects did not explain this decline. Among women with obstetric complications, there appeared to be a secular increase in use of abdominal-pelvic region x-ray films, though this was not significant. Finally, there was a marked drop in x-ray films of other body regions, largely due to discontinuation of routine chest x-rays in 1959–1960. During the time period studied, changes in x-ray equipment and technique were made at Kaiser Oakland and at many other U.S. hospitals which reduced the amount of radiation delivered so that a substantial decline in fetal x-ray exposure probably occurred, even though changes in abdominal-pelvic region x-ray use were minimal.