[Use of ultrasonography by a Chinese-made B-scan real time apparatus in early pregnancies].
D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011258:Pregnancy Tests / Q000295:instrumentation; D011261:Pregnancy Trimester, First; D014465:Ultrasonics / Q000295:instrumentation; D014463:Ultrasonography