The placenta is an important organ for material exchange between the fetus and the mother, and its main functions are material exchange, defense and synthesis. 1. Function of material exchange: When the fetus develops in the mother, the respiratory system is immature and needs the placenta for gas exchange. In addition, the nutrients needed by the fetus are obtained from the mother through the placenta. 2. Defense function: the defense function of the placenta depends on the selectivity of the placental barrier. Due to the existence of the placental barrier, the placenta will not receive all the substances from the mother, and thus will play a certain role in defense against viruses and bacteria. 3. Synthesis function: the placenta can synthesize a variety of hormones, enzymes, cytokines, such as human chorionic gonadotropin, estrogen, progesterone, etc., which can help the growth and development of the fetus. In addition, the placenta also has immune function, metabolic regulation function, etc. If the function of the placenta is reduced, it will have adverse effects on the fetus. If a pregnant woman discovers that her placenta is hypoplastic during a pregnancy test, it is recommended that she consult a doctor in a timely manner and receive symptomatic treatment under the doctor’s guidance.