Mild early pregnancy reactions have little effect on the pregnant woman and her fetus and do not require special treatment. However, early pregnancy reactions with severe symptoms and long duration, such as severe vomiting, can affect the development of the fetus and maternal health. Wernicke’s encephalopathy can cause stillbirth, miscarriage, and maternal death. The fetus in the mother’s body from the fertilized egg to the maturity of the embryo, the entire growth and development of the mother needs to draw nutrients, the later the pregnancy, the more nutrients required. The first 3 months of pregnancy is the initial stage of fetal development, the pregnant woman’s body mass grows slowly; in the middle of pregnancy, the pregnant woman’s body mass grows rapidly the mother’s body starts to reserve fat and some proteins, the uterus, breasts, fetus, placenta, amniotic fluid, blood volume are growing rapidly the pregnant woman’s body mass grows about 4-5kg; in the late pregnancy the mother needs to grow body mass about 5k; the whole pregnancy body mass grows about 12kg. However, the prolonged vomiting and loss of appetite of pregnant women lead to the reduction of maternal nutritional intake, which cannot provide sufficient nutrition to the fetus, and out of the protective mechanism of the organism, the energy stored in the mother’s body will be used at this time, causing the mother-to-be to lose weight and reduce resistance, which limits the fetal development. The key point of nutritional intake during pregnancy is balanced nutrition; lack of nutrition causes fetal growth restriction, while excess nutrition can lead to a huge baby. No matter lack or excess of nutrition, it will cause some metabolic diseases in the fetus as an adult after birth. For the sake of the baby in the belly, mothers should remember to have a balanced nutrition during pregnancy.