The birth of a new life is a great mystery. Today, the doctors have at their disposal devices that allow them to "look" into the intrauterine world, and yet we do not yet know all the subtleties of the future person's development, but we can judge the state of the baby, basically, only by the heart rate (heart rate). Future mothers with anxiety and trepidation listen to themselves, with a sinking heart, expect the results of ultrasound or CTG - is everything good with a crumb? Protocols of research, as a rule, contain different values: the heart of the child is constantly evolving, so the norms of the fetal heart rate can vary significantly by week.
Fetal heart rate in the first trimester
The heart of the embryo is formed on 4-5 weeks of pregnancy. And already at week 6, the fetal heartbeat can be "heard" with a transvaginal ultrasound sensor. During this period, the heart and nervous system of the baby are not yet immature, so in the first trimester there are norms of fetal heart rate for weeks , allowing the doctor to track the development and condition of the baby. The values of fetal heart rate for weeks are given in the following table:
| Term of pregnancy, weeks. | Heart rate, ud./min. |
|---|---|
| 5 (onset of cardiac activity) | 80-85 |
| 6th | 103-126 |
| 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 | 157 (146-168) |
Please note that from the 5th to the 8th week inclusive, HR rates in children at the beginning and at the end of the week (heart rate increase) are given, and from the 9th week of pregnancy the average heart rate and their tolerances are given. For example, the fetal heart beat at 7 weeks will be 126 beats per minute at the beginning of the week and 149 beats per minute at the end. And at 13 weeks the fetal heart rate, on average, should be 159 beats per minute, normal values will be considered from 147 to 171 beats per minute.
Fetal heart rate in the second and third trimester
It is believed that from the 12-14 weeks of pregnancy and until childbirth the heart of the child should normally perform 140-160 beats per minute. This means that the fetal heart rate at 17 weeks, 22 weeks, 30 and even 40 weeks should remain approximately the same. Deviations in one direction or another indicate a child's unhappiness. With rapid (tachycardia) or a thinned (bradycardia) heartbeat, the doctor, in the first place, will suspect intrauterine hypoxia of the fetus. Tachycardia indicates a mild oxygen starvation of the baby, which appears as a result of a long stay of the mother in a stuffy room or without movement. Bradycardia speaks of severe hypoxia, resulting from fetoplacental insufficiency. In this case, serious treatment, and sometimes emergency delivery with caesarean section (if long-term therapy does not work and the fetus's status is steadily deteriorating) is necessary.
At 32 weeks gestation and later fetal heart rate can be determined using cardiotocography (CTG). Along with the cardiac activity of the child, CTG registers contractions of the uterus and motor activity of the baby. On late pregnancy
There are other causes of the violation of the fetal heart rhythm: a pregnant woman's illness, her emotional or nervous overexcitation, physical activity (for example, gymnastics or walking). In addition, the heart rate of a child depends on his motor activity: during periods of wakefulness and movements, the heart rate increases, and during sleep a small heart beats less often. These factors should be taken into account in the study of cardiac activity of the fetus.