Usually fish oil DHA products are most effective when taken during the middle and late pregnancy (after 20 weeks of pregnancy) to 6 months after the birth of the fetus. This is because this is the period when the neurons in the fetal brain center are dividing and maturing the fastest, and also the period when the need for DHA is the greatest. Especially after the fetus reaches 5 months of gestational age, due to the imposition of fetal education content, artificially increase the stimulation of the fetus’ auditory, visual and tactile sensory neural pathways, which will cause more dendrites or dendritic spines to grow in the neurons of the relevant sensory centers on the fetal cerebral cortex. At this time, it is necessary for the mother to supply more DHA to the fetus in order to meet the fetal demand for DHA. Therefore, it is recommended that pregnant women take DHA supplements from the fourth month of pregnancy. In addition, pregnant women can also take a-linolenic acid supplements to synthesize DHA from the mother’s blood, and then deliver it to the fetus through the blood or breast milk. It is usually recommended that pregnant women consume not less than 400mg of DHA per day, while daily foods such as linolenic acid-rich walnuts and other nuts can be synthesized into DHA by the liver after intake, so it is recommended that pregnant women determine how much additional DHA should be supplemented according to their own diet.