The chances of 4D ultrasound screening a child for harelip are very high, up to 90% and above. The main purpose of 4D ultrasound is to screen the fetus for malformations, and it can clearly show the development of the face and organs of the fetus. It can make early diagnosis of fetal malformations, such as cleft lip and palate, abnormal development of bones, brain and internal organs. Therefore, doctors can judge whether the fetus has hare lip by observing whether the fetal lip line is continuous or not, if it is not continuous, it means the fetus has hare lip. Generally, the chance of the 4D ultrasound checking the child’s harelip is very high, up to 90% and above. Even a slight harelip can usually be seen by ultrasound, and pregnant women can choose whether to continue the pregnancy according to the degree of harelip. With the advancement of society, cleft lip can be treated after birth. The probability of cleft lip is clinically detected at a high rate. You need to pay more attention after pregnancy to avoid exposure to risk factors to reduce the chance of cleft lip and ensure eugenics.