Ultrasound of the third trimester: child development norms, possible pathologies and recommendations of gynecologists

2024 Author: Priscilla Miln | [email protected]. Last modified: 2023-12-16 00:21

The day is fast approaching when the expectant mother will become real and see her long-awaited baby. There comes a decisive third trimester, when the social status of the baby officially changes. Now he is turning from a fetus into a child.

Third trimester. What's going on with the baby?

The third trimester lasts from 28 to 40 weeks and will be marked by active growth and development of the baby. During this period of time, the child begins to accumulate subcutaneous fat and becomes more and more like a newborn. Already at 32 weeks, he will reach a weight of about 1.8 kg and will become about 28 cm long. Before giving birth, he will gain more body weight up to 3-3.5 kg, he will have wakefulness and sleep cycles, and he will start sucking his thumb hands, preparing to suck on the mother's breast. In the third trimester comes the finish line. Now your little one is getting more active, smiling and frowning, breathing exercises and getting ready to go out into the world.

Ultrasound. When do they?

This period is the most informative. Therefore,Ultrasound of the fetus in the third trimester. And at this time, not only the usual ultrasound examination is prescribed, but also the planned mandatory third screening. This regular examination is very important for assessing the current condition of the fetus and its position before the onset of childbirth. In the third trimester, which week will the doctor prescribe an ultrasound? As a rule, district gynecologists send the expectant mother for a scheduled regular ultrasound examination at about 30-33 weeks. But in some cases, it can be carried out according to indications and in periods from 28 to the thirtieth week, and at 34-36 weeks.

What does an ultrasound show? What pathologies can be identified?

An ultrasound in the third trimester is a mandatory procedure for every pregnant woman. It is completely painless, but it makes it possible to identify possible pathologies of the fetus at an early stage or to obtain final confidence in the impeccable he alth of the child. In addition, this procedure allows you to determine the weight of the baby in the womb, as well as its gender. Moreover, ultrasound of the fetus in the third trimester allows you to find out the exact dimensions of the fetal head and torso. It is also possible to assess the condition of the placenta and determine the exact position of the fetus in the uterus.

Third trimester ultrasound data is unique information that accurately shows all measurements, norms and possible deviations from them, which only a qualified specialist can decipher. Based on the results of such an examination, the doctor makes a decision regarding the general he alth of the woman and her fetus. if necessaryprescribes additional studies or gives a referral for hospitalization. If there are any deviations from the norm, ultrasound in the third trimester will help to detect them and specify them with the help of an additional examination. In this period of pregnancy, a Doppler study of the fetal vessels and umbilical cord arteries is shown. Since their work is very important for the cardiovascular system of the future crumbs.

In addition, ultrasound in the third trimester allows you to determine whether the fetus receives enough nutrients and oxygen to exclude the development of hypoxia and other cardiac pathologies. The information obtained gives an expanded idea of the course of pregnancy and the intrauterine development of the unborn child. These indicators are important not only for the doctor, but also for ensuring the peace of mind of the expectant mother. But if the period allotted for the third trimester of pregnancy is fourteen weeks, then when is the most optimal time for a routine study? In the third trimester, which week does ultrasound show more accurate and reliable results?

Screening

The best time for a scheduled screening ultrasound is 30-32 weeks. It was at this time that there is already enough information about all the necessary parameters that, according to the norms, the fetus should achieve, as well as the state of the placenta and uterus. In addition, since the child becomes more active at this time, attention should be paid to the location of the fetus, where its arms, legs, head are located, whether the fetus lies correctly and whether there are anypathologies in his organs. Therefore, those who are interested in the question of when an ultrasound is done in the third trimester can be answered that the most effective period is 30-32 weeks. Although you can do it at 29 weeks, but then everything will be more blurry and difficult to distinguish. When the research indications are fuzzy, it is difficult to track the appearance of genetic abnormalities and the development of the baby's organs, it is not even always possible to clearly determine its gender. As a rule, women try to do exactly at week 30 to do an ultrasound in the third trimester. The dates are already such that they allow us to consider everything thoroughly, but the birth is still far away.

What points are paid special attention to during ultrasound?

At this time, attention is paid to such points as:

• The position in which the fetus is in relation to the mother's uterus. If it is located upside down, then there is no cause for concern, the child lies normally, takes the correct position. But it often happens that the unborn child is located across and across and the doctor gives him a period of 2-3 weeks to take a normal position. If during this period the coup has not occurred, mommy will be prepared for a caesarean section so as not to harm either the baby or his parent.
• Sufficiency of amniotic fluid, because it is when an ultrasound is done in the third trimester that one can detect such a deviation from the norm as oligohydramnios or polyhydramnios. Both the first and the second are very dangerous for expectant mothers, as they indicate the presence of any infections in the body.
• Wrapping the baby with the umbilical cord -a fairly common deviation, and at this time it is even possible to determine a double entanglement. If the fact of entanglement with the umbilical cord is confirmed by ultrasound, then only a caesarean section is recommended by specialists - in the process of natural birth, the child may simply be strangled by his own umbilical cord during the passage of the birth canal.
• The degree of maturation of the placenta - if it has matured ahead of schedule, corresponding to the stage of pregnancy, then the woman should be constantly monitored so that premature contractions and childbirth do not begin, moreover, with the early maturation of the placenta, the child will experience a lack of nutrients and oxygen.
• Only an ultrasound in the third trimester allows you to most accurately determine the weight of the unborn baby, which is of great importance in a narrow pelvis of a pregnant woman, when the doctor has doubts whether she will be able to give birth on her own.
• Fetometry. These are the parameters for measuring the volume of the fetus - the head, abdomen, hip length, because it is by these indicators that the gestational age is determined. Having found deviations, the doctor is obliged to conduct an extended phytometry procedure - he measures the circumference of the head in the frontal-occipital part and considers its percentage with other measurements. Then he re-measures the tummy and compares it with the measurement of the femur. After measurements, the doctor examines the brain, considering the state of the vascular plexus, the size of the lobes of the brain and cerebellum, which is required to check for the presence of brain diseases and intrauterine infections that can negatively affect motor andswallowing capacity of the child. After that, the doctor examines the structure of the nose, lips, eyes and spine.
• The condition of the fetal organs - especially the lungs and heart. If his diaphragm is underdeveloped, then the lungs will not correspond to the norm. To check cardiac activity, the correct operation of valves, vessels and partitions, a special study is carried out - cardiotocography, which allows you to determine the heart rate and check the entire cardiac activity of the system. This procedure can be carried out only after 32 weeks, otherwise the diagnostics will provide inaccurate data.
• The state of the abdominal cavity - the coherence of the work of the intestines, liver, kidneys and bladder is checked. Of the pathologies, abnormalities in the kidneys most often occur.

Is an ultrasound harmful to a baby in the womb?

At 30-32 weeks, ultrasound is performed by simply driving the sensor along the wall of the pregnant woman's abdomen. This is a completely harmless procedure, since the ultrasonic waves used in the device do not harm either the future mother or her fetus. This is especially important to know for those who are interested in how often to do an ultrasound in the third trimester. Since today ultrasound is the most effective and safest way to conduct high-quality diagnostics during pregnancy, the recommendations of doctors in such cases cannot be neglected. Only this method of research is able to identify potential pathologies at an early stage and reduce the risk of their occurrence even before the birth of a child.

Almost every womanwho had frequent third trimester ultrasounds, worries about harming her unborn baby. But you shouldn't worry about it. Since it has been proven by medicine that at this frequency, on which the devices operate, there is no harmful effect either on the pregnant woman herself or on her unborn child. This is an absolutely routine procedure, which is prescribed by a doctor even at later stages of pregnancy, if it is necessary to follow the development of one or another organ of the fetus. Dopplerometry is used to assess blood circulation, which studies the vascular network, placental blood flow and the baby's cardiac function in more detail.

Norms of indicators and measurements of the fetus

If the doctor ordered an ultrasound in the third trimester, what week is the best time to take fetometric measurements and what is their rate? Possible deviations from the norm in the development of individual organs of the child may indicate a physical underdevelopment of the fetus. Control measurements of various parameters of the fetus are made in the period from 32 to 34 weeks. They should normally correspond to the following indicators:

• biparietal head size - 78-82 mm plus or minus 7 mm;
• frontal-occipital part - 104-110 mm plus or minus 9 mm;
• head circumference - 304-317 mm plus or minus 21-22 mm;
• tummy coverage - 286-306 mm plus or minus 28-30 mm;
• femur length - 61-65 mm plus or minus 5 mm, leg bones - 56-60 mm plus or minus 4 mm, humerus - 56-59 mm plus or minus 4 mm, forearm bones - 49- 52 mm plus or minus 4 mm.

As ofplacenta - its localization, thickness, structure, degree of maturity specify various important points: if the placenta is located close to the pharynx of the uterus, there may be a risk of fixing the head in the wrong state. The thickness of the placenta can vary from 32.2 mm up to 43.8 mm, if there is a discrepancy between the parameters, then the function of the intake of nutrients into the body of the fetus is impaired. The structure of the placenta should be as homogeneous as possible. Otherwise, there is a high probability of the development of any inflammatory process.

Uterine amniotic fluid should have an exclusively vertical diameter and be in a free area measuring from 20 to 70 mm.

Pathologies that can be detected at this time

In the third trimester, pregnancy is already moving towards its successful completion and this period is characterized by the following possible pathologies that are detected by ultrasound:

• mal position of fetus;
• deviation in the amount of amniotic fluid;
• wrapping the baby with the umbilical cord;
• degree of placental maturity;
• inconsistency in fetometric measurement parameters;
• pathology of the heart, lungs and abdominal organs.

Doctors' advice to expectant mothers

Gynecologists recommend that pregnant women strictly follow the instructions of the leading doctor and pay attention to their physical condition and psychological state. After all, the third trimester brings to the life of the expectant mother a lot of inconvenience caused by an increase in the size of the uterus, fear of impending childbirth, pain inlower back, displacement of internal organs, shortness of breath, frequent urination, periodic constipation, varicose troubles. In addition, there is a feeling of anxiety and fear. Doctors recommend that during this crucial period, you should carefully monitor that your he alth is normal. If there are signs of preeclampsia or placental abruption, or any other problems with the body, seek help from a medical facility. Only the well-being of the expectant mother can serve as a true indicator of a favorable pregnancy. Any deterioration should be considered as a reason to visit a doctor.

Small conclusion

Now you know when to do an ultrasound for a pregnant woman in the third trimester. We have reviewed all standards. They also named possible pathologies that can be seen on ultrasound. We hope this information will help you bear a he althy baby. Having reached all the features of the course of the third trimester of pregnancy, you will be able to listen more carefully to your body, which will certainly warn you about an imminent meeting with your child.