Inadequate nutrition during pregnancy is harmful 1. Inadequate nutritional intake during pregnancy will have a very negative impact on both the pregnant woman and the fetus; 2. lack of iron, vitamin B12 and folic acid during pregnancy may lead to malnutrition anemia; 3. lack of calcium and vitamin D will lead to osteochondrosis and osteoporosis; 4. lack of protein will lead to malnutrition edema; 5. lack of carbohydrates will lead to hypoglycemia, etc.; 6. 6, deficiency of folic acid before and during early pregnancy can lead to malformations of fetal nervous system development; 7, insufficient energy and carbohydrate intake can lead to low birth weight; 8, insufficient protein intake can lead to impaired fetal brain development; 9, iodine deficiency during pregnancy can lead to fetal cretinism; 10, low serum vitamin D levels during pregnancy, the fetus may develop ” rickets”; 11, severe nutritional deficiency can cause fetal miscarriage, premature birth or even fetal death in the womb. In addition, gestational hypertension syndrome, preterm delivery, premature rupture of membranes, weak contractions during labor, postpartum hemorrhage, insufficient lactation, puerperal infection, etc. are also associated with malnutrition during pregnancy. Many pregnant women only consider the fetus to absorb more nutrients, so once pregnant, they eat hard and take all kinds of supplements, rather than lacking, however, this is an unscientific way of nutrition intake. However, this is an unscientific way of nutritional intake. As opposed to under-nutrition, over-nutrition during pregnancy is a condition that occurs more often in pregnant women nowadays. Therefore, overnutrition during pregnancy is undesirable. Macronutrient overload and maternal and infant weight abnormalities: on the one hand, overnutrition in pregnant women can lead to obesity, increase the probability of gestational diabetes and gestational hypertension, which is not conducive to fetal growth, and also makes it difficult for pregnant women to deliver and to recover their bodies after delivery; on the other hand, overnutrition can also lead to the birth of huge babies, increasing the possibility of difficult deliveries and It is easy to have birth injuries. On the other hand, over-nutrition may also lead to the birth of a huge baby, increasing the likelihood of difficult delivery and birth injuries. Therefore, pregnant women should pay attention to diet control to maintain the fetal weight within the normal range, diversify diets, eat natural foods as much as possible, avoid high-salt, high-sugar and stimulating foods, especially some high-sugar fruits, increase energy intake reasonably, and divide meals scientifically. Abnormal micronutrient supplementation and fetal malformation: Calcium supplementation is not the more the better. Excessive calcium supplementation not only risks getting kidney stones and milk base syndrome, but also causes premature calcification of the placenta and premature closure of fontanelle. The right amount of vitamin supplementation can prevent some congenital defects in the fetus, but if it is too much it can be counterproductive.