tokens: Objectives of the current study were to compare results between Sprague - Dawley ( SD ) and Wistar strains when ASA is administered on GD 9 , 10 , or 11 ; to compare the malformation patterns following single and multiple dosings during organogenesis in SD rats ; and to test the hypothesis that maternal gastrointestinal toxicity confounds the detection of low incidence malformations with ASA when a multiple dosing paradigm is used .