Level 1: Fetal development at three months of pregnancy. The fetus at three months of pregnancy has completed the first trimester of pregnancy and has begun to enter the second trimester. At this time, the fetus has formed its head, neck, trunk, limbs and other basic parts, and has begun to grow and develop. At this time, the fetus is about 7-10 cm in length and weighs about 30 grams. At this stage, the fetal organs also begin to gradually improve. , the heart has been able to beat independently, and its beating can be observed through ultrasound examination; the liver and kidneys have also begun to function and can excrete