 a placental sample will be taken either the patient delivered preterm or at term term patients will be either control term group or patients with successful treatment of preterm labor. The placental sample taken should have part of the decidua and then the sample will be fixed in 10 neutral-buffered formalin for 24-48 h, routinely processed, embedded in paraffin wax, sectioned at 3 μm thickness, and mounted on 3-aminopropyl-triethoxysilane -coated slides. Serial sections will be immunostained for CD 16 and CD56 . Immunohisto-chemistery study will be done at Ain Shams Maternity Hospital Histopathology department. 