Bearing down at the time of delivery and the incidence of spinal headache in parturients.
D000293:Adolescent; D000328:Adult; D000773:Anesthesia, Obstetrical / Q000009:adverse effects*; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D002555:Cerebrospinal Fluid / Q000502:physiology; D005260:Female; D006261:Headache / Q000209:etiology* / Q000517:prevention & control; D006801:Humans; D007743:Labor, Obstetric; D009339:Needles; D011247:Pregnancy; D011446:Prospective Studies; D011897:Random Allocation