The first week: the egg and sperm unite to form a fertilized egg, which divides several times to form a cell mass that gradually grows, partly assimilating into the fetus and partly becoming an accessory organ that supplies the fetus with nutrients and protects the fetus; the second week: the little life grows rapidly, forming the spine, brain tissue, spinal cord, and nervous system have a certain shape; the fourth week: the heart appears, then the limbs sprout, eyes and ears appear, and lungs and liver The seventh week: at this time, fingers and toes begin to appear on the hands and feet, and eyes are clearly visible. The whole appearance is similar to that of a toddler and can move in the amniotic fluid; the eighth week: all the organs of the embryo have their original shape; the third month: the head of the fetus accounts for 1/2 of the full length of the fetus at this time, and the growth is accelerated later, and the body weight doubles at the end of the twelfth week; the fourth month: the fetus reaches 16 cm in length, the legs become relatively long, and the bones are rapidly ossified; the fifth month: the pregnant woman can feel the fetal movement of the fetus in the abdomen. The sixth month: both arms are bent in front of the chest and both knees are raised to the abdomen; the seventh month: the fetus is about 35cm long and weighs 1000g; the eighth month: the fetus is about 40cm long and weighs 1700g. The fetus is moving freely in the uterus, the fetal movement is coordinated, the position is basically fixed, and the head is facing downward; the tenth month: the fetus is finished developing, it is about 50cm long and weighs 3000g. The skin is white with a slight pinkish tinge, there is a layer of white fat on the surface of the body, the chest is well developed, it will burp and suck its own thumb.