The fetal lips usually begin to develop between 8 and 10 weeks of gestation and finish developing around 16 weeks. In the 5th week of pregnancy, some of the embryos protrude and gradually fuse with each other to form the face, and around the 8th-10th week of pregnancy, the lips also begin to develop, and if the lips do not develop normally during this period, it will cause the appearance of lip deformities. If the lips do not develop properly during this period, it will cause lip deformity. After that, when the pregnant woman is 3 months pregnant, the fetus is basically formed. The first trimester of pregnancy is an important period for the development of fetal organs. If the pregnant woman has regular nervousness, rubella and other viral infections, or uses anti-tumor drugs or antihistamines during this period, it may lead to fetal lip deformities and abnormalities such as “harelip”. Pregnant women can undergo a 4D examination between 22 and 28 weeks of pregnancy to rule out abnormalities. During pregnancy, especially in early pregnancy, pay attention to nutritional intake, avoid viral infections or injuries, develop good lifestyle habits, pay attention to proper rest, try to avoid too much strain or mental tension, do not drink and smoke, and go to the hospital for regular maternity checkups. Avoid consuming drugs with high side effects or excessive radiation exposure to avoid fetal malformations.