When mothers-to-be have their regular maternity checkups starting from the archives, they will have their blood drawn for routine blood tests. Many of you may be told by your doctor that you are mildly anemic, which means that your hemoglobin level is below 110g/L (but greater than 90g/L). After pregnancy, due to the increase in blood volume of pregnant women during pregnancy, the hemoglobin in the blood can be relatively lower; moreover, the growth and development of the fetus requires a large amount of nutrients, and anemia can occur when the intake of iron, folic acid and vitamins is relatively insufficient causing a further drop in hemoglobin. Therefore, mild anemia during pregnancy is a common physiological phenomenon, so there is no need to be nervous, and appropriate iron and folic acid supplementation and increased dietary nutrient intake will be sufficient. However, if moderate to severe anemia (hemoglobin level below 90g/L) occurs, or if iron supplementation is ineffective, you need to visit a hematologist. In the routine blood test, besides the hemoglobin value, the doctor will further pay attention to the mean red blood cell volume (MCV, normal value 80-100fl). If the MCV is large (greater than 100fl, especially greater than 120fl), it is most likely due to megaloblastic anemia caused by folic acid and vitamin B12 deficiency, and the diagnosis can be confirmed by checking intraerythrocyte folic acid and serum vitamin B12 levels. If MCV is small (less than 80fl), it is most often seen in iron deficiency, and serum iron, total iron binding capacity, transferrin saturation and ferritin can be checked. However, if iron supplementation therapy is ineffective, or if the MCV is particularly small (less than 60fl), the possibility of hereditary thalassemia needs to be considered. Further clarification is needed by asking family history, checking hemoglobin electrophoresis or even screening for common thalassemia genes. Treatment of common nutritional anemias in pregnancy is generally simple and effective. Iron deficiency anemia can be treated with oral iron supplements such as ferrous succinate or iron polysaccharide complexes, and oral vitamin C can help with iron absorption. Iron supplements are usually taken after meals to reduce the stimulation of the gastrointestinal tract, and the stool will be black after taking iron supplements, which is caused by drugs. A small number of pregnant women may experience stomach discomfort or constipation after taking iron supplements. Megaloblastic anemia can be treated with oral supplementation of folic acid. Thalassemia is a hereditary disease, caused by abnormal hemoglobin synthesis due to gene mutation or deletion. There is no medication to treat it, but usually the thalassemia found by the mother-to-be’s maternity checkup is mild thalassemia, which has no obvious effect on the pregnant woman herself and does not require treatment. The focus of concern is whether it will be passed on to the fetus and how much it will affect the fetus. Next, the father-to-be will be screened for hemoglobin electrophoresis or thalassemia genetics based on the birthplace of the husband, family history, whether he is anemic and the size of his red blood cells. If the father-to-be has no evidence of thalassemia, there is a 1 in 2 chance that the fetus will be a completely normal child, and a 1 in 2 chance that it will be thalassemia minor like the mother, and that its normal growth and development will not be affected. However, if the father-to-be is also found to be homozygous for thalassemia, there is a 1 in 4 chance that the fetus will have moderate to severe thalassemia, and will be prone to stillbirth or preterm delivery, and may require blood transfusions to maintain life after birth due to progressively increasing anemia. Therefore, DNA prenatal diagnosis through chorionic villus, amniotic fluid or umbilical cord blood sampling is required.