First of all, we must understand that the fetus has been growing and developing in the pregnant mother, from the combination of sperm and eggs to test-tube embryos, and then form the fetus. His brain, human bones and all human organs are constantly growing and improving. This is an ever-changing whole process. In this link, the fetus may cause problems at any time and anywhere because of sex chromosome gene mutation, virus infection, drugs, radiation sources and other factors.
Take Tang Ping for example. The diagnostic rate of Tang Ping is only 50%~60%, which is the data of official website. In fact, it is doubtful whether it is that high. During pregnancy, prenatal examination is a very critical examination, which is beneficial to eugenics. During prenatal examination, doctors can find abnormal pregnancy and solve it immediately, and find problems. However, the new project of prenatal examination did not cover all symptoms, so the first five prenatal examinations said that the child was fine, and the second examination said that the child was unhealthy, which may happen. Because many fetal abnormalities are hidden in the early stage, they are not good or can't be detected. Only when it reaches a certain stage can it be detected according to prenatal examination.
Secondly, the special success of pregnancy examination does not mean that the fetus is completely healthy physically and mentally, but the probability of any problems is extremely low and is often ignored. During pregnancy, the fetus is a whole process of growth and development. The health status of different human organs is different, and each examination is different according to the situation. It is very likely that these aspects were not investigated in the first five times, and problems were found in the sixth inspection. Moreover, each pregnant mother's check-up time and frequency during pregnancy are different. According to the schedule of prenatal examination, the sixth prenatal examination is B-ultrasound, and if the pregnant mother's prenatal examination is more rigorous, then the sixth prenatal examination is four-dimensional color Doppler ultrasound. Four-dimensional color Doppler ultrasound is an abnormal examination of the limbs and face of the fetus, so it will find that the fetus is unhealthy.
Have I made myself clear to everyone?