It is usually normal for the baby to be one week too big, which may be caused by miscalculation of the pregnancy week, over-nutrition during pregnancy, and genetic factors. 1. Miscalculation of pregnancy week: Women usually have irregular menstrual cycles, shorter menstrual cycles, can’t remember the last menstrual period, ovulation time is advanced, and the wrong calculation of pregnancy week may lead to the fetus being one week too big. 2. Excessive nutrition: often overeating during pregnancy, eating too much food, the nutrients are all absorbed by the fetus, will also show that the fetus is one week large. 3. Genetic factors: the parents are taller and the fetus is also bigger due to genetic factors, and the fetus will be one week bigger in the pregnancy test. Fetal macrosomia within the range of two weeks is generally normal, usually also need to do a good job of pregnancy checkups, to understand the development of the fetus in the womb.