title: Brief communication: effects of diagnostic irradiation during pregnancy on head circumference at birth.
abstract: A historical cohort study was carried out to evaluate the effects in utero medical ionizing radiation on head circumference at birth. The nature of medical practice in Rochester, Minnesota, and the Mayo Clinic medical records linkage system enabled us to provide accurate estimates of medical radiation absorbed dose in 9,793 pregnancies of 2,980 women pregnant in Rochester between 1917 through 1973. Data were controlled for sex of the fetus, duration of pregnancy and congenital head abnormalities. It was found that medical ionizing radiation in the second and third trimesters of more than 300 mrad were related to significantly decreased head circumference. There was no significant effect of radiation exposure in the first trimester or periconceptional period. Medical ionizing radiation in the second and third trimesters of more than 300 mrad is related to a significant yet minimal, decreasing head circumference at birth. Maximum effects were seen during the midgestational and second trimester periods.
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: N I
authors.initials: NI
authors.lastname: Bohnen
authors.forename: M W
authors.initials: MW
authors.lastname: Ragozzino
authors.forename: L T
authors.initials: LT
authors.lastname: Kurland
mesh_terms: D002508:Cephalometry; D015331:Cohort Studies; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging; D005333:Fetus / Q000528:radiation effects; D006257:Head / Q000033:anatomy & histology / Q000196:embryology / Q000528:radiation effects*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010053:Ovary / Q000528:radiation effects; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011829:Radiation Dosage; D011859:Radiography / Q000009:adverse effects; D011878:Radiotherapy / Q000009:adverse effects; D012189:Retrospective Studies