In the clinic, we often see babies with hand and foot deformities such as polydactyly, syndactyly, thumb hypoplasia or missing fingers. After explaining the treatment options to the parents, many mothers ask why our baby’s hands (feet) are deformed? In fact, the causes of hand and foot deformities in babies are not yet clear, but may be related to the following factors: First, the mother’s health, because the lack of various vitamins and trace elements may lead to abnormal development of the baby; Second, recognized research shows that smoking (including second-hand smoke) will increase the possibility of hand deformities, a large-scale epidemiological survey in the United States found that if the mother has a long-term A large-scale epidemiological survey in the United States found that if the mother has a history of long-term exposure to smoking, the chances of hand deformities in children increased significantly; Third, formaldehyde, toluene, xylene, glycol ether solvents and other solvents in paint may also lead to the occurrence of hand deformities. Some of our treated children have a history of exposure to similar compounds in early pregnancy; fourth, physical factors such as radiation are also possible factors. Therefore, during the 4-8 weeks of pregnancy, mothers-to-be must be careful to avoid the disturbance of external abnormal physical and chemical factors, as most of the hand malformations involving environmental factors will be formed during this period. Some mothers have paid great attention, but their babies still have hand and foot deformities. At this time, mothers should not blame themselves and feel guilty, but just solve the problem when it arises and actively cooperate with our doctor’s treatment.