Generally, you can start to build a card in the third month of pregnancy, that is, 12 weeks of pregnancy, when the fetus has developed and formed by ultrasound examination, and the period of easy abortion has passed because the placenta has been formed and the pregnancy is more stable. At this time, the fetus is growing and developing faster, we should pay attention to ensure the supply of nutrients, we can eat more protein-rich food, such as eggs, milk, soy milk, we also need to eat more fruits and vegetables rich in vitamin C. We should have a balanced diet and reasonable nutrition, we can’t be partial and picky. A reasonable mix of meat and vegetables will help you get enough nutrients, vitamins and trace elements to promote healthy fetal growth.