The third trimester belly does not change significantly. Usually when a pregnant woman is in her third trimester of pregnancy, that is, at 12 weeks, the uterus has just slowly risen from the pelvic cavity to the area above the entrance of the pelvis, but it has not yet fully entered the lower abdomen; therefore, it is not possible to see obvious changes in the abdomen, and at the same time it is not possible to get a concrete picture of the size of the changes in the belly of the pregnant woman. If you want to see a visible change in the belly, it usually takes about 16 weeks, because at this time the uterus will gradually increase in size and enter into the lower abdomen, so that it is possible to see a visible change from the pregnant woman’s belly. If you are already 12 weeks pregnant, it is recommended that you should pay more attention to rest in your daily life; at the same time, you should not have sex during this period because the fetus has not yet stabilized in the uterus, so as to avoid causing miscarriage; you should have regular maternity checkups, and you should consult a doctor immediately when any discomfort occurs.