The best time period to take folic acid is from the beginning of pregnancy preparation until the second trimester of pregnancy, at least from the first trimester to the second trimester of pregnancy. Taking folic acid can reduce the probability of neural tube defects in the fetus, because the fetus needs a large amount of folic acid for neurological development of the brain, and the development is in the early stages of pregnancy. Taking folic acid during the preparation period can improve the quality of egg cells and semen, so as to achieve eugenics. During this period of time, you also need to pay attention to timely quit smoking, quit drinking, strengthen exercise, enhance physical fitness, improve immunity. It is also necessary to strengthen the intake of nutrients, especially calcium, iron and high-quality protein intake, to avoid affecting the quality of fertilized eggs. Pay attention to ensure sufficient sleep time and sleep quality, try to avoid cold and flu, because infection, especially in early pregnancy, can easily lead to fetal malformation.