Placental Invasion Ability Assessment

The placental invasion ability assessment was conducted following the methodology outlined in a previous study [18 (link)]. The percentage of interstitial trophoblast invasion into the mesometrial triangle (MT) was utilized to quantify the invasion ability, with infiltrated trophoblast cells identified using a cytokeratin-7 (CK-7) antibody (Abcam, ab181598). Evidence of spiral artery (SA) remodeling was also identified through the presence of CK-7-positive cells arranged on a fibrinoid layer, alongside the absence of α-actin-positive smooth muscle cells. Additionally, the cross-sectional area, as reported by Cotechini et al., was included as an informative indicator [19 (link)]. Both the ratio of the cytokeratin-7-positive trophoblast cell area to the MT area and the cross-sectional areas were measured using image J analysis software.