Objective:To study the pathological mechanism for spontaneous abortion by determining apoptosis and expression of Bcl-2 as well as Bax in decidua tissue of spontaneous abortion models and normal pregnancy mice.Methods:The abortion-prone CBAXDBA/2 matings were established as the model of spontaneous abortion and the nonabortion-prone CBAXBALB/c matings were used as the model of normal pregnancy.SABC was used to detect the expression of Bcl-2 and Bax in decidua tissue of spontaneous abortion and normal pregnancy at day 13 of gestation.Medical color-image measure system for immune-histochemistry was used for semiquantitative analysis.Apoptosis was detected by in situ TUNEL assay.Results:In decidua tissue of the spontaneous abortion models, Bcl-2 expression was lower and Bax was higher than it that of normal model (P