Effect of antepartum diagnostic roentgenography on the white blood cell count of the newborn infant.

Abstract

The effect on the white blood cell count of the newborn infant of diagnostic roentgenography of the mother late in pregnancy does not appear to have been studied. Teratologic consequences of embryonal exposure to irradiation during the first trimester are known. The fact that the fetus receives total-body irradiation in both these situations suggests that, if the dose is adequate, exposure such as that produced in x-ray pelvimetry might produce a measurable leukopenia. The results of the present study indicate that there is no significant change in the newborn infant's white count induced by diagnostic maternal roentgenography and, further, that the radiation dose is ordinarily too small to produce such an effect. Material and Methods The white blood cell count of all normal term infants admitted to the newborn nursery of the University of Minnesota Hospitals during this study was made by routine laboratory methods. All infants admitted in the twenty-four hours prior to the five weekday mornings were studied until 125 infants had been examined. The counts on a pair of twins subsequently proved to have erythroblastosis fetalis and on a premature infant found to be sick were discarded. Most of the counts were done in duplicate on separate pipcttings of heel blood. All results checked within 10 per cent. For the summaries the first count recorded was used. The names of the mothers were subsequently obtained from the Obstetrical Department records and cross-checked against the Radiology Department's files. All abdominal x-ray films obtained during the period of obstetrical care at the University Hospitals were recorded. As a cross-check, this list was compared with Obstetrical Department pelvimetry reports. There is no reason to believe that any cases were missed. The technician doing the white blood cell counts had no way of knowing which infants' mothers did or did not have x-ray examination. Results The mean white blood cell count of infants born after abdominal x-ray studies of their mothers during late pregnancy was 19,391, as compared to 19,732 for the unirradiated controls. This is not a significant difference. See Table I. Fourteen of the 22 infants were exposed to irradiation in the last fourteen days of pregnancy, 3 of these on the day of delivery. Twenty of the 22 exposures were within thirty-one days of delivery. When the white blood cell counts were ranked by the number of days from exposure to delivery, no trend could be found. One mother had fourteen abdominal x-ray examinations within four weeks of delivery. The infant had a white blood cell count of 16,100. The majority of the irradiated mothers had been subjected to pelvimetry by the precision parallax shift method, involving the use of pairs of anteroposterior and lateral films. When indicated, these films were repeated, so that for most patients four to eight films were obtained.