Furthermore, 175 DEGs were identified at 21 d, and those genes are mainly distributed in 20 pathways, such as PI3K-Akt signalling pathway, tumour necrosis factor signalling pathway, MAPK signalling pathway, and Hippo signalling pathway, COL6A3, THBS1, fibronectin 1, and ITGB4 are all DEGs in PI3K-Akt signalling pathway at 21 d, and the expression profiles of COL6A3 suggested that it play an important role in pregnancy, and miscarriage was initiated by its abnormal expression [25]. Here, ITGB4 is linked to spontaneous abortion.