A simple and informative way to assess the condition of the baby during the third trimester of gestation, in the first (during labor) and second (during attempts) labor, is to monitor the cardiac activity and contractions of the mother’s uterus. What week do CTGs take? The study can be conducted from the twenty-eighth week, but often the most accurate indicators can be obtained only from the thirty-second week. This is an effective and safe diagnostic method, which has no contraindications, so expectant mothers may not worry about their health or the well-being of the baby.
What is cardiotocography?
Why do CTGs for pregnant women? Cardiotocography is a painless, simple and effective method for studying the frequency of contractions of the heart of the fetus and the reduction of the walls of the uterus of the mother. The indicators are recorded by special sensors, pass through the device and applied to a paper tape or reflected on the monitor. Deciphering the results allows the doctor to assess the condition of the child in several ways. Therefore, expectant mothers are often interested in when they do the first CTG. It is worth noting that the diagnostic method is used exclusively in the third trimester, because previously it is impossible to get a high-quality record.
CTG allows you to determine a number of anomalies, although there are more advanced methods for diagnosing the condition of the child. With the help of cardiotocography in late pregnancy and during childbirth, it is possible to detect heart disease, foci of infection or inflammation, anemia, impaired blood flow, entanglement of the umbilical cord, the presence of a node on the umbilical cord, determine the degree of influence of the mother’s diseases on the baby’s condition and the effectiveness of certain medications.
Some of the above pathologies can lead to fetal death of the fetus or disability of the child. Oxygen deficiency, for example, can cause cerebral palsy, gastrointestinal dysfunction, hypertension, renal failure, seizures, seizures, and so on. In some cases, the correction of detected abnormalities can be carried out during pregnancy. CTG also helps to make the best decision (that is, safe for the mother and the baby) regarding the delivery method.
When do CTGs during pregnancy
Cardiotocography is a safe way to assess the condition of the fetus, so the procedure is prescribed for many pregnant women. What week do CTGs take? Recording is in the third trimester. You can do CTG already from the 28-30th week of pregnancy, but even at these dates you still can not get reliable results. The final formation of the cycle, when the period of motor activity of the fetus is regularly replaced by rest, occurs only from the thirty-second week of pregnancy. When conducting diagnostics and evaluating the results, it is also worth considering that the duration of the fetus sleep is on average thirty minutes.
How long do CTGs begin to be pregnant? In the normal course of pregnancy, the first procedure can be prescribed at about thirty-two weeks. Starting from this period, CTGs are performed no more than once a week. The usual frequency is once every ten days. In the presence of pregnancy complications, but favorable previous results, the study is carried out every five to seven days, as well as with changes in women's well-being. With hypoxia, CTG is done daily or every other day until the child's condition normalizes or before a decision is made on early delivery.
Optimal time of day
The optimal time for recording is the period of the biophysical activity of the fetus, that is, the interval between 9 and 14 hours, as well as between 19 and 24 hours. Diagnosis is performed on an empty stomach or two hours after a meal, during or within an hour after glucose administration. If time is not respected for any reason, and deviations from the norm are determined, then a second recording must be carried out in compliance with all the rules. This is due to the fact that the body of the child is completely dependent on the mother. In addition, the level of sugar in the blood of a woman can affect the motor activity of the fetus and the ability to respond to stimuli.
CTG during childbirth
What week do CTGs take? As already mentioned above, cardiotocography is prescribed approximately for a period of thirty-two weeks. But in some cases, the control of fetal heart rate and uterine contractions is first carried out only in the first stage of labor. If the pregnancy is uncomplicated, then listening to the fetal heartbeat with an ordinary obstetric stethoscope may be enough. This is a wooden tube, which the doctor puts on the stomach of the expectant mother at each appointment.
During normal childbirth, the baby usually has enough opportunities to overcome difficulties encountered in the process, but it is possible to interrupt the supply of oxygen, which leads to hypoxia. This condition is dangerous because it can lead to irreversible reactions. Therefore, a CTG is mandatory in childbirth. In the first period, records are sufficient every three hours. The second period of childbirth is sometimes generally recommended to be carried out under the continuous monitoring of the CTG apparatus. If there are indications, the frequency of the study is determined by the doctor individually.
In many domestic hospitals, three examinations on the CTG apparatus are considered mandatory: upon admission to the maternity ward with contractions, immediately after the amniotic fluid is discharged and before the onset of attempts. In the presence of indications monitoring is carried out more often. The study presents some inconvenience for a woman, because it is difficult to remain stationary during contractions, but sometimes CTG can not be dispensed with. This procedure is especially important when applying epidural anesthesia, chronic fetal hypoxia, labor weakness, pregnancy, gestosis and some other complications.
Indicators for regular recording
From about the 31st week, CTGs are performed once a week if suspicious indicators were not detected during the first procedure. But there are cases that require constant monitoring. Indications for regular recording are multiple or post-term pregnancy, prolonged exposure of the infection to the body of the expectant mother, diabetes mellitus, polyhydramnios or oligohydramnios, chronic diseases in women, hemolytic disease (maternal and child incompatibility by blood group or Rh factor), uterine scar , bad habits, preeclampsia in combination with seizures and high blood pressure, history of miscarriage or abortion, spotting, prolapse of the umbilical cord or entanglement around the fetal neck. In childbirth, constant monitoring is indicated for weak labor, the appointment of birth control, the introduction of epidural anesthesia, in case of chronic fetal hypoxia, a postponed or premature pregnancy, multiple pregnancy, and late toxicosis.
How is the study
CTG at the 37th week, later or earlier, is carried out according to the same algorithm. In the treatment room, the expectant mother will be offered to lie down on the couch. Half-sitting is preferred, but some patients prefer to lie on their left side. The nurse will attach special sensors to the stomach, which are fixed by straps. The upper one will fix the tone of the uterus, and the lower one - fetal heart rate. The gel is used to lubricate only the second sensor. Then the recording process is carried out. Results are transferred to paper tape.
Some CTG devices are not equipped with an automatic recorder of fetal movements, so the doctor may ask the patient to pick up a special remote control and press the button when the child is active. If the indicators are favorable, the study usually lasts no more than 15-20 minutes. Often, the diagnosis takes from 45 to 90 minutes, because it can occur during the period of sleep of the child. It is important to remember that the results of the study can be affected by the emotional mood of the expectant mother, stress, malnutrition, or exposure to weather conditions.
CTG indicators: normal
Decryption of CTG is necessarily carried out by a doctor, but you can independently understand the results. During the study, fetal heart rate, basal heart rate (contractions of the heart muscle lasting for ten minutes and in the intervals between contractions), changes in basal heart rate, slowing or accelerating heart rate for 15 seconds or more are evaluated. Normally, CTG at 30 weeks and at a different time should show the following results: basal rhythm - from 120 to 160 beats per minute, the amplitude of the basal rhythm - 5-25 beats per minute, the absence of heart rate slowdowns of 15 or more beats per minute for 15 seconds or more, two or more short-term heart rate accelerations during ten minutes of recording.
Decoding CTG: what do the points mean?
To simplify the interpretation of diagnostic results, a scoring system is proposed. What do the CTG scores mean? The normal condition of the fetus is 8-10 points. A score of 5-7 points indicates the initial signs of oxygen deficiency. In this case, you need to repeat the recording within a day. If the result does not change, then additional research methods are needed: Dopplerometry, assessment of the fetus by ultrasound. A score of 4 or less indicates serious changes in the condition of the child. It is necessary to immediately make a decision on emergency delivery or intensive care until normal indicators.
Zero points are set for basal heart rate, if the indicator is less than 100 beats per minute or more than 180, one point - with a heart rate of 100-120, 160-180, two points - 120-160. If there are no accelerations in heart contractions during fetal movement, then zero points are put for this indicator, in the presence of periodic accelerations - one point, with acceleration in each movement - two points. In the absence of deceleration of the heart rhythm, two points are set, with short-term decelerations - one point, with long-term decelerations - zero points. In the same way, according to the table, heart rate variability and amplitude are estimated.
Heart Rate Assessment
What determines CTG? During the diagnostic procedure, the condition of the fetus is assessed by heart rate, variability of contractions, deceleration or acceleration of the heart rhythm. The rhythm of contractions of the heart muscle should normally be 110-160 beats per minute. The minimum and maximum indicators in this case are not of interest to the doctor, here the average values are important. To independently interpret the results, you need to move the printed paper tape to the distance of your outstretched arm and imagine or draw a straight line with your finger on the schedule. The level along the vertical axis will be the average rhythm.
Heartbeat variability
On the curves of the CTG graph there are many small cloves and several large ones. Small ones show deviations from the rhythm. Normally, there should be no more than six in a minute, but calculating the exact number is not so simple, so doctors often estimate the amplitude of the deviations - the average changes in height, which normally are no more than 11-25 beats per minute. If the change in height is 0-10 beats in the same period of time, then this may indicate deviations. But this indicator is normal if the baby is sleeping or the gestational age does not exceed twenty-eight weeks of weeks. If the estimated rate rises to 25 beats per minute or more, then the doctor may suspect hypoxia or entanglement of the umbilical cord around the neck.
Evaluation of increases and decreases
When evaluating the contractions and increases, the doctor draws attention to the large teeth on the CTG graph. When a child is active, his heart beats faster. On the graph, this is reflected in the form of a large tooth, directed upward. In ten minutes of research, such increases should normally be no more than two. With CTG, increases may not be detected. Do not panic, because the child during the diagnosis can just sleep. Harnesses are big teeth on the chart, looking down. High-amplitude contractions can alert the doctor, but the result must be evaluated along with the second schedule, on which uterine contractions are recorded.
Invalid study metrics
From what week do CTGs be done to get the most reliable results? Diagnosis can be carried out from the twenty-eighth week of pregnancy, but the exact indicators, most likely, will be able to fix only closer to 32 weeks. But even at this time, the results can be greatly distorted under the influence of certain factors. Excessive activity of the child or a period of rest, insufficient amount of conductive gel on the sensor, high BMI of the mother (extra kilograms), and consumption of plentiful food immediately before the study can affect the indicators. The results may be unreliable in multiple pregnancy. Sometimes the condition of the future mother and fetus is affected by adverse weather conditions, emotional mood, or previous stress.
Is CTG harmful during pregnancy?
Cardiotocography is a completely safe procedure, for which there are no contraindications. The method does not do any harm to either the mother or the child. If necessary, the recording can be repeated for a long time and even daily. This examination provides enough information and helps to identify possible violations and threats in time, as well as take the necessary actions in a timely manner. The results obtained should be considered in combination with data on the general nature of the course of pregnancy and in connection with the indications of other studies, in particular, Dopplerometry and ultrasound.
It is important to remember that the results of CTG are not the final diagnosis, but only one way to assess the condition of the child. In childbirth, for example, the nature of the recording alarms the doctor with a short-term disturbance of blood flow in the vessels due to compression of the umbilical cord by the baby’s head. But there is no harm to the fetus. Rarely, but doctors are faced with the opposite situation: CTG does not cause concern with prolonged hypoxia. This can happen if the fetus as a result of a protective reaction reduces the need for oxygen. The condition of the child is unsatisfactory. In this regard, in case of any deviations, additional diagnostic procedures and tests may be performed.