Weight management during pregnancy varies according to pre-pregnancy weight. Pregnant women who were thin before pregnancy should gain 12.5-18 kg during pregnancy; those with normal pre-pregnancy weight should gain 11.5-16 kg during pregnancy; and pregnant women who were obese or overweight before pregnancy should gain 7-11 kg during pregnancy. Weight gain during pregnancy is also an effective indicator to determine whether nutrition during pregnancy is reasonable. A high pre-pregnancy body mass index (BMI) is associated with poor adherence to nutritional control during pregnancy, and excessive weight gain is associated with complications such as pre-eclampsia in the late stages of pregnancy, which may have an impact on the prognosis of both mother and child.