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As always, the third trimester sonographer begins by walking his sensor over the entire surface of our abdomen. The fetus is already too big for him to see it in its entirety, but stopping on the skull, the femurs, the doctor manages to take measures. This data is essential to ensure that the baby continues to grow normally. At this stage of pregnancy, it weighs between 1, 4 and 2 kg and measures almost 40 centimeters, all his organs are functioning and he will be ready to go out soon. In theory, at this stage, we can know more or less how much the baby will weigh at term. During this ultrasound, we can also know the sex of our child if it was not visible before.
Vitality, development … a very thorough examination
The sonographer continues his examination by focusing on the organs which may have developed a pathology since the 2nd ultrasound, in particular the brain, heart and kidneys. For example, it checks that the communications that have been established between the heart and the atria are normal or that the kidneys are functioning properly. Another important aspect of this test: make sure the baby is moving well, that he makes hand movements, that his face becomes animated and that he swallows normally, which for the specialist also means that he is breathing well. The examination can be supplemented by a Doppler study of the blood flow in the vessels supplying the uterus, in order to check the quality of the exchanges between the mother and the child, and therefore the feeding of the fetus via the placenta.
Third ultrasound: the presentation of the baby
Baby’s upside down already ? Perfect. Ready for the big trip, he will likely stay in this position until childbirth. Is it in the seat (buttocks down) or in a transverse position? We do not panic, he can still turn around and a new ultrasound at 37 weeks of pregnancy will make sure. If this is not the case, the gynecologist will order a CT scan to measure our pelvis. If it is wide enough, we can give birth vaginally. Otherwise, a cesarean will be scheduled. The placenta that connects us to our child since early pregnancy sometimes has the bad idea of getting between the fetus and the cervix, preventing the baby from coming down. But again, this is not necessarily definitive and a new ultrasound in a few weeks will allow you to see if the placenta has changed position. If this is not the case, the birth will have to be done by cesarean section, and parents and doctors will have time to prepare for it.
Third ultrasound: the state of health of the future baby?
When it reveals a cardiac or renal pathology, for example, the third ultrasound also makes it possible to plan special care or monitoring from birth. Thus, when the ultrasound shows an abnormally large bladder, due to poor drainage from the kidneys, the baby will be taken care of, from birth, by the pediatrician of the maternity hospital. He will benefit from a complete assessment, increased surveillance and possibly preventive antibiotic treatment. If this third ultrasound makes it possible to detect a cardiac pathology, the sonographer will put the future parents in contact with a cardiopediatrician so that they can jointly consider the care of the baby after his birth.