Friction between the fetal head and uterine wall during normal labor and lower uterine spasm.
D005260:Female; D005333:Fetus; D006257:Head; D006801:Humans; D007743:Labor, Obstetric; D008433:Mathematics; D007744:Obstetric Labor Complications / Q000503:physiopathology*; D011247:Pregnancy; D011312:Pressure; D013035:Spasm / Q000503:physiopathology*; D014591:Uterine Diseases / Q000503:physiopathology*; D014599:Uterus