Moderate anemia but large fetus can be caused by obesity or gestational diabetes. When a pregnant woman has moderate anemia but a large fetus during pregnancy, the anemia does not necessarily affect the fetus. If a pregnant woman eats too much or does not exercise during pregnancy, it can lead to obesity, which can result in a large fetus. In addition, when a pregnant woman with moderate anemia herself develops a large fetus during pregnancy, she may also develop gestational diabetes during pregnancy. Gestational diabetes mellitus is mainly caused by a series of changes that occur during pregnancy, most patients do not have obvious symptoms, some patients will have symptoms such as elevated blood glucose, polyphagia, etc., which can also lead to fetal enlargement. Therefore, it is recommended that pregnant women with moderate anemia but large fetuses should go to the hospital in time for examination, and follow the doctor’s instructions to deal with the cause of the disease.