In the past, pregnant women used to come to the hospital only when they were about to have a baby. In recent times, people have become more aware of eugenics and may come back to the hospital for checkups in the 4th-5th months of pregnancy. However, it is still a bit late, and the best time for checkups should be at least 2-3 months of pregnancy earlier. The best time to come back to the hospital for prenatal checkups is at least 2-3 months of pregnancy. Case 2; 11 weeks’ gestation, high risk of early prenatal screening, ultrasound indicated thickened NT and upper limb malformation, chromosome 18 in fetus by chorionic villus examination, abortion at 12 weeks. Case 3: 11 weeks’ gestation, low risk of prenatal screening, ultrasound showed fetal giant bladder and bilateral hydronephrosis, 1 week review of bladder enlargement. Fetal chromosomal examination was refused and the bladder occupied almost the whole fetal abdomen on 16 weeks repeat examination, posterior urethral valves were considered and labor was induced. Fetal chromosomes were normal in amniotic fluid culture. These are just a few of the typical cases. There are many similar cases. As you can see, prenatal screening and ultrasonography in early pregnancy can detect some of the fetal abnormalities at an early stage, perform the relevant tests at an early stage, and terminate the pregnancy if the abnormality is determined to require abortion alone. It avoids more pain caused by inducing abortion in the middle or later stages of the pregnancy.