Since a previous experiment revealed that late stage pregnancy exposure of CF-1 mice to high frequency noise resulted in a significant increase in fetolethality, the hormonal/biochemical correlates of this effect were sought. Since corticosterone levels were measured in a previous experiment (see ES 50044) and to be unaffected by noise exposure, this experiment focused on catecholamines, because exogenous introduction of these substances has been found to increase fetolethality. Exposure period was 12 hours (noon to midnight).