The safety of ultrasound.
D000028:Abortion, Induced; D000653:Amniotic Fluid; D002869:Chromosome Aberrations; D046508:Culture Techniques; D005260:Female; D005318:Fetal Heart; D006801:Humans; D011247:Pregnancy; D014464:Ultrasonic Therapy; D014465:Ultrasonics / Q000009:adverse effects*; D014463:Ultrasonography