The incidence of placental calcification in normal pregnancies.
D002114:Calcinosis / Q000175:diagnosis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D010298:Parity; D010922:Placenta Diseases / Q000175:diagnosis*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D012621:Seasons; D014463:Ultrasonography