The placenta is the link between the mother and the fetus, and is an important organ for providing nutrients to the baby. The detailed functions are as follows: 1. Oxygen, carbon dioxide and water are exchanged by simple diffusion, which is equivalent to the respiratory function; glucose is the main energy source for fetal metabolism; amino acids, phosphorus, iodine and calcium are all transported through the placenta in an active way. The products of fetal metabolism are then eliminated from the body with the mother through the placenta. 2, the placenta resists various foreign viruses, most of the drugs have extremely limited effects, and most of them can affect the fetus through the placenta. Bacteria and mycoplasma, which cannot pass the placental barrier, can form foci in the placental area, which can also cause embryonic and fetal infections. 3, the placenta can synthesize hormones, cytokines, enzymes, etc. that play a role in pregnancy. 4, normal pregnancy mother can tolerate and not reject the fetus, the specific mechanism is not very clear, consider the relationship with the placenta. The placenta plays a vital role in the growth and development of the fetus, if abnormal development, placental abruption, etc. may cause fetal death and life-threatening to the pregnant woman. Regular checkups during pregnancy, usually pay attention to the abdomen not to be subjected to external forces, and seek medical attention whenever abdominal pain occurs.