Pregnant women 4 months pregnant, has entered the mid-pregnancy, the mother and fetus need a lot of rich nutrition, in addition to pay attention to nutritional balance, but also according to the growth of the fetus needs and pregnant women’s physical state supplementation of the required substances. 1, folic acid: folic acid can be involved in the synthesis and metabolism of the human body’s genetic material and proteins, which can effectively prevent fetal malformations and congenital heart disease; in addition, folic acid can also promote the growth of placental development, the role of the placental is mainly responsible for the delivery of nutrients to the fetus and the transport of excreta. In addition, folic acid can also promote the growth and development of the placenta, the placenta is mainly responsible for the role of the fetus to transport nutrients and transportation of excreta, the function of its good or bad can have a direct impact on the growth and development of the fetus; folic acid also promotes the absorption of iron, can effectively prevent the occurrence of iron-deficiency anemia in pregnant women. Pregnant women in the daily diet of folic acid will be destroyed in the process, can be under the guidance of the doctor, supplementation of folic acid-rich nutrients; 2, iron, calcium elements: after 4 months of female pregnancy, there will be a part of the iron and calcium into the fetus and placenta, to participate in, and assist in, the growth and development of the fetus. Pregnant women lack of iron may appear anemia, resulting in dizziness and shortness of breath, calcium deficiency is prone to lead to their calf twitching, fetal congenital rickets, etc., so you need to supplement a larger amount of calcium and iron. Calcium-rich foods include dairy, beans, eggs and seafood, such as milk, soybeans, tofu, eggs, shrimp, etc.; iron-rich foods include red meat, nuts and other dark-colored foods. If the body is very deficient in trace elements, it is necessary to supplement through some drugs, it is recommended that the diet under professional guidance, to avoid malnutrition or overnutrition; 3, vitamin D: vitamin D can regulate calcium metabolism in pregnant women to maintain the health of the bones of the body, with the role of preventing rickets. If the pregnant woman lacks vitamin D, pregnant women can appear bone softening, head sweating, teeth easy to break and other symptoms. Pregnant women through the umbilical cord for the fetus to transport nutrients, pregnant women lack of vitamin D can directly affect the fetal bone development and the formation of tooth enamel. Pregnant women can supplement vitamin D by consuming vitamin-rich foods, such as animal liver, egg yolks, eggs, fish, etc., as well as by sunbathing and moderate exercise.