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Prenatal heartbeat (usually called embryonic heartbeat before approximately 10 weeks of gestational age and then fetal heartbeat until birth) is the contractions during the cardiac cycles of an embryo or fetus. In cases of early pregnancy bleeding, the detection of prenatal heartbeat is the main finding that distinguishes a viable pregnancy from a silent miscarriage. ==Acquisition== In the first trimester, heartbeat can be visualized and the heart rate quantified by obstetric ultrasonography. A study of 32 normal pregnancies came to the result a fetal heartbeat was visible at a mean human chorionic gonadotropin (hCG) level of 10,000 UI/l (range 8650-12,200). Obstetric ultrasonography can also use doppler technique on key vessels such as the umbilical artery can detect abnormal flow. In later stages of pregnancy, a simple Doppler fetal monitor can quantify the fetal heart rate. During childbirth, the parameter is part of cardiotocography, which is where the fetal heartbeat and uterine contractions are continuously recorded. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prenatal heartbeat」の詳細全文を読む スポンサード リンク
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