With the popularization of parenting knowledge, once pregnant with a baby, mothers-to-be are careful not to play with the computer, all-weather radiation suit protection, do not dare to eat and drink at will, etc., when doing ultrasound examinations are also nervous and worried about the health of the baby in the belly, with doubts, so now let’s learn about those things about ultrasound during pregnancy. There are many mothers who have ultrasound examinations and ask the question, “Does it affect the development of the baby? First, let’s understand what ultrasound really is. Ultrasound is a kind of sound wave, produced by the mechanical vibration of an object, whose frequency is greater than 20,000Hz exceeding the upper threshold of human ear hearing. Generally speaking, the harm caused by ultrasound to human tissue is mainly determined by the power of ultrasound and the length of the examination time, just like anything, there is a degree, too much is not good, but in an appropriate amount, there is no harm to the human body. The ultrasound examination is within this appropriate degree, and some domestic and international studies and follow-ups have not found any damage to the fetus from ultrasound. Therefore, ultrasound examinations during pregnancy generally have no effect on the baby, but to be prudent, in early pregnancy, if there is no medical need, you should avoid ultrasound as much as possible and listen to the doctor’s arrangement, and control the number and duration of the examination. The ultrasound examinations are usually performed four times during pregnancy, as follows: 1. Early pregnancy ultrasound (before 14 weeks): During this period, the uterus, adnexa, position of the gestational sac, fetal head and hip length, fetal heartbeat, fetal number, etc. Early ultrasound can determine the size of the fetus and be used to calculate the expected date of delivery. 2. 2.Mid-trimester ultrasound (18-24 weeks): The most important ultrasound examination to detect most fetal congenital abnormalities must be performed in this period. This examination is mainly to observe the fetal anatomy (including fetal head, face and neck, chest, abdomen, spine and limbs), placental position, amniotic fluid, etc. The fetal size is measured and the fetal growth is evaluated to see if it corresponds to the month of menopause. This examination can exclude some structural abnormalities of the fetus, but not all congenital diseases, because there are different degrees of congenital abnormalities, and some congenital abnormalities are developmental and appear only in the second trimester, in addition, ultrasound is also limited by the intrauterine conditions of the pregnant woman (such as obesity, too much and too little amniotic fluid, fixed fetal position, etc.), which affects the detection rate. 3.Late pregnancy ultrasound examination (28-32 weeks): This examination is mainly to assess the growth and development of the fetus, and to do a screening for structural malformations of the fetal system (due to factors such as oversized fetus, fetal bone obscuration and relatively fixed fetal position, this examination cannot be comprehensive and detailed, but only a relatively rough screening for malformations) and to screen for some malformations that occur only in late pregnancy. At this time, a 3D ultrasound can be used to create a 3D image of the baby’s face. If the conditions are good, the baby’s five senses can be clearly presented, and the lips, nose and eyes can be distinguished one by one. 4.Prenatal ultrasound assessment (full term, before birth): This examination is to determine the fetal position, assess the fetal growth and development indicators as well as the estimated weight of the fetus. It should be emphasized that the detection rate of malformation screening is very low at this time. The most suitable for the three-dimensional 4D during the pregnancy detoxification Finally, a misconception needs to be corrected. Many mothers-to-be believe that 3D and 4D ultrasound is the highest level of screening for fetal malformations, but in fact, 3D ultrasound is a three-dimensional imaging of the local body surface of the fetus, which is a good assistance and supplement to 2D ultrasound. Previous ultrasound images are two-dimensional ultrasound images, showing the organs or structures of the cross-sectional images, ultrasound physicians can observe and diagnose them, and ordinary people difficult to identify; three-dimensional, four-dimensional ultrasound is built on the basis of two-dimensional ultrasound, can have the entity, real-time in the present three-dimensional shape and structure, so that the ultrasound diagnosis from the plane image up to the level of three-dimensional images, to improve the accuracy of diagnosis. For example, prenatal 3D and 4D ultrasound can clearly show the fetal facial structure, enabling the mother-to-be to see the baby’s face. It can also show the whole three-dimensional image of the fetus when the gestational week is small. In fact, the classification of prenatal ultrasound is graded according to the time of pregnancy and the content of the examination of the fetus. Mothers-to-be must have heard of black and white ultrasound, color ultrasound, 3-D ultrasound, 4-D ultrasound, abdominal ultrasound, vaginal ultrasound, and so on and so forth. These are all different ultrasound techniques that are used for different needs in ultrasound examinations. Prenatal ultrasound can be used to get the best results depending on the trimester and the content of the fetus being examined.