The heart of the fetus begins to form from the fourth week. Starting from the sixth week of pregnancy, the measurement of fetal heart rate is determined with the help of special equipment - a transvaginal ultrasound sensor. When determining the rates of growth and development of the baby, heart rate indicators are among the main ones. Any pathological changes in the development processes affect the heart rate and thus signal problems that have arisen.
The frequency of normal fetal heart rate depends on the period of pregnancy. Below in the table the norms of correspondence of the HR to the term of pregnancy are given.
| Term of pregnancy, weeks. | Heart rate, ud./min. |
|---|---|
| 5 | 80-85 |
| 6th | 102-126 |
| 7th | 126-149 |
| 8 | 149-172 |
| 9 | 175 (155-195) |
| 10 | 170 (161-179) |
| eleven | 165 (153-177) |
| 12 | 162 (150-174) |
| 13 | 159 (147-171) |
| 14-40 | 157 (146-168) |
Fetal heart rate by weeks
From the fifth to the eighth week the heart rate increases, and starting from the ninth week, the fetal heart beats more evenly (possible deviations are indicated in parentheses). After the thirteenth week, during the control of the heartbeat of the fetus, the heart rate is normally 159 bpm. In this case, a deviation in the range of 147-171 bpm is possible.
If there is a deviation from the normal heart rate, the doctor conducts an examination for the presence of intrauterine hypoxia in the fetus. A rapid heartbeat indicates a mild form of oxygen starvation, and a bradycardia (an eructated palpitation) is a severe form. The mild form of hypoxia of the fetus can come through a prolonged stay of the mother without movement or in a stuffy room. The severe form of hypoxia comes through fetoplacental insufficiency and requires serious treatment.
Fetal heartbeat monitoring
Cardiac activity of the fetus is assessed using ultrasound, echocardiography (ECG), auscultation (listening) and CTG (cardiotocography). In most cases, only ultrasound is used, but if there are suspicions of pathologies, then additional studies are used. For example, the echocardiogram of the fetus, in which attention is concentrated only on the heart. With the help of ECG, the structure of the heart, its functions, large vessels are examined. The most optimal period for this study is the period from the eighteenth to the twenty-eighth week.
Starting from the thirty-second week, CTG can be performed, in which the heartbeat of the fetus and uterine contractions are simultaneously recorded.