title: Letter: Ultrasound and safety.
mesh_terms: D004247:DNA; D005260:Female; D005333:Fetus / Q000166:cytology; D006801:Humans; D009153:Mutagens; D009691:Nucleic Acid Denaturation; D011247:Pregnancy; D011296:Prenatal Diagnosis; D014465:Ultrasonics / Q000009:adverse effects*
chemical_list: D009153:Mutagens; D004247:DNA