High platelets in the 30th week of pregnancy can be caused by physiologic factors, and this condition is not harmful. If infection and other factors cause, can cause harm to mother and child. 1. Physiological factors: normal people are generally lower in the morning and higher in the afternoon, lower in the spring and higher in the winter, and platelets may also increase mildly after exercise. At the same time, high coagulation state during pregnancy, itself is also higher than normal. This situation does not need to be dealt with, regular review can be. 2. Infections and other factors: when pregnant women have bacterial or viral infections, or combined with blood system problems, it may lead to platelet increase. Increased platelets lead to hypercoagulability of the patient’s blood, which makes it easy to form microthrombi. If blood clots appear in the placental area, it can affect the blood supply of the fetus, which can lead to risks such as miscarriage, fetal growth restriction, and also cause pregnant women to suffer from hypertensive disorders of pregnancy and other risks. Thirty weeks pregnant with high platelets, it is recommended to improve the examination to find out the cause of the disease, if necessary, under the guidance of the doctor to use drugs to treat. It is recommended to drink more water and take appropriate activities to avoid thrombosis. Keep up with your checkups and observe the development of the fetus.