Acute radiation exposure is known to cause biological damage that leads to severe health effects. However, the effects and subsequent health implications of exposure to low doses of ionizing radiation are unclear. The purpose of this study was to investigate the effects of low-dose ionizing radiation exposures in utero. Pregnant laboratory mice (BALB/c) were exposed to low-dose Chernobyl radiation 10-13 mSv per day for 10 days during organogenesis. The progeny were born and weaned in an uncontaminated laboratory, then were exposed to an acute radiation dose (2.4 Sv). Analysis of our end points (litter dynamics, DNA damage, bone marrow stem cell function, white blood cell counts and gene expression) suggests that a low-dose (100-130 mSv) in utero exposure to ionizing radiation is not deleterious to the offspring. Rather DNA damage, white blood cell levels, and gene expression results suggest a radioadaptive response was elicited for the in utero exposure with respect to the effects of the subsequent acute radiation exposure.