The fetus is an adorable “parasite” within the mother’s body. From the size of a grain of rice fertilized egg developed into a few kilograms of fetus, a grass, a tree, a brick and a tile are taken from the mother’s body. Therefore, the nutritional requirements of pregnant women are higher than those of non-pregnant women, and are closely related to fetal growth and intellectual development. However, it is important not to overdo it and become overnourished, and it is necessary to control and monitor the weight change of pregnant women at the right time for the benefit of the health of both mother and child. Pregnant women need special care because they have an important mission – to nurture human life. Pregnant women supply all the nutrients needed for the growth and development of the fetus through the placenta, which is a transit point. After about 280 days, a single-celled fertilized egg in the uterus develops into a newborn weighing several kilograms. Maternal nutrition will have a crucial impact on the outcome of the pregnancy and is related to the health of the child throughout its life. The nutrition of the fetus comes entirely from the mother, while the nutrition of pregnant women is obtained from food, so the nutrition of pregnant women not only affects their own health, but also directly affects the growth of the fetus and the development of the brain, heart and other tissues and organs. And the fetus is usually “very selfish”, even if the mother’s intake of nutrients is not enough, the fetus also want to absorb calcium, iron, protein and other nutrients from the mother’s body, so that the mother out of more than in, and prone to calcium, iron, protein and other nutrient deficiencies. Generally speaking, pregnant women gain a total of 10 kg to 12.5 kg during pregnancy. In addition to the weight of the fetus, this includes an increase of 1.5 kg in blood, 1.2 kg in extracellular fluid, 1.3 kg in the uterus and breasts, 3.0 kg in fat, and 1.5 kg in the placenta and amniotic fluid. Monitoring the weight change of pregnant women can initially determine the nutritional status of the pregnant woman and the growth of the fetus. As long as the weight gain is within the normal range, the nutrition and exercise during pregnancy are generally well-balanced. It is important for pregnant women to develop the habit of monitoring their weight throughout pregnancy. The more ideal rate of weight gain is as follows: 1, 1 kg to 2 kg in early pregnancy; 2, in the middle and late stages of pregnancy, 0.3 kg to 0.5 kg per week, with a total increase of 10 kg to 12 kg (7 kg to 9 kg for obese pregnant women); 3, for those who gain less than 0.3 kg or more than 0.55 kg per week, energy intake should be adjusted under the direction of a doctor.