5 months of pregnancy, the fetus is about to enter the rapid growth stage, the heartbeat is very active, the brain is gradually developing and differentiating, able to feel the sense of hearing, touch and other senses, at this time the most fear of external influences, interference with the growth and development of the fetus, the following common factors affecting: 1, toxic substances: toxic substances are divided into natural toxic substances and synthetic toxic substances. Natural toxic substances contain certain wild mushrooms, berries and other plants, as well as toxins contained in animals such as puffer fish. Synthetic toxic substances include dioxins, melamine and other chemicals, these toxic substances may cause fetal growth retardation, low weight, or fetal malformation or even death; 2, noise: 5-6 months of pregnancy, the fetal hearing gradually developed, stronger or longer duration of external noise may damage the hearing of the fetus. In addition, noise can also affect the quality of sleep and mood of pregnant women, thus damaging the health of pregnant women and fetuses; 3, parasites: parasites can cause damage to the health of pregnant women, including Toxoplasma gondii serious infection can even lead to fetal development malformations. Many pets may have residual toxoplasma in their feces, so during pregnancy, pregnant women had better not touch animals and family pets; 4, pregnant women are emotionally unstable: emotional stability can not only reduce the probability of pre-eclampsia miscarriage, but also reduce the probability of fetal mental illness after birth. Therefore, pregnant women should keep themselves emotionally stable; 5, malnutrition: May pregnancy belongs to the middle of pregnancy, belongs to the fetus needs a lot of nutritional supplements period, pregnant women should pay attention to nutritional supplements, such as eating more high-quality protein food and fresh vegetables, fruits.