Fetal growth restriction (FGR), also known as placental dysfunction syndrome or fetal malnutrition syndrome, refers to a fetal weight that is lower than the 10th percentile of the average weight for its gestational age or lower than 2 standard deviations of its average weight. Fetal growth and development are closely related to many factors, such as the external environment of the pregnant woman, the pathological and physiological conditions of the pregnant woman's body, the placenta and umbilical cord, the internal environment of the fetus itself, and the sperm situation before pregnancy. If these factors affect the reduction of the number of fetal cells or the abnormal cell size, it can lead to small or large babies.