Shallow invasion could result in pathological processes of placenta leading to fetal growth restriction (FGR) in singletons and twins. Osteopontin (OPN) plays an important role in trophoblast invasion. Shallow invasion could result in pathological processes of placenta leading to fetal growth restriction (FGR) in singletons and twins. Osteopontin (OPN) plays an important role in trophoblast invasion.