Antepartum Dental Radiography and Infant Low Birth Weight

PREPUBERTAL, ADOLESCENT, AND pregnant females exposed to ionizing radiation may be at an increased risk for delivering a low-birth-weight (LBW) infant ( 2500 g). In prepubertal girls, high-dose therapeutic radiation for childhood cancers has been associated with an increased risk for future LBW offspring, and a direct relationship has been reported between the radiation dose and LBW risk. In adolescents, diagnostic radiation for idiopathic scoliosis was also associated with a dose-dependent increased LBW risk. In pregnant women, medical x-ray radiation, not dental xray radiation, has been associated with an increased LBW risk, and exposure to the atomic bomb explosion in Hiroshima during early pregnancy has been associated with offspring of small stature and head circumference. These latter effects occurred at very low doses, the lowest yet known to produce grossly detectable effects in the offspring of exposed mothers. It is currently unclear whether radiation affects the reproductive organs directly, or thyroid function and thereby indirectly pregnancy outcomes, or whether factors unrelated to radiation are responsible for the LBW. Because dental diagnostic radiography results in measurable radiation doses to the hypothalamus-pituitarythyroid axis and not the reproductive organs or the fetus, it provides an opportunity to test the role of the hypothalamus-pituitary-thyroid axis in the radiation-LBW association. The goal of this study was to evaluate whether dental radiography influences the likelihood for a LBW infant in a populationbased case-control study.