Pregnant women with a fever of 38°C have an effect on the fetus, the degree of which depends on the duration of the fever, the primary illness and its accompanying symptoms, and the week of pregnancy. Fever can cause metabolic disorders and produce toxins in the body, which can enter the placenta through blood circulation, thus affecting the growth and development of the fetus. The body of pregnant women in early pregnancy is relatively sensitive and their immunity is low, so they are susceptible to fever caused by common cold, which usually has less impact on the fetus. It is necessary to cool down physically in time and drink more warm water to promote metabolism. If the fever is caused by other diseases, such as nephritis, pneumonia, hyperthyroidism, etc., timely medical attention should be sought. If the fever is prolonged, it can have a great impact on the fetus, which can lead to miscarriage and fetal malformation in early pregnancy and premature birth and fetal distress in the middle and late stages, and the fetal mortality rate is also high. Since many therapeutic measures or medications cannot be used during pregnancy, fever in pregnant women is usually treated symptomatically. Adults have a relatively strong immune system and can metabolize and excrete the toxins produced by fever, but fetuses have a weaker immune system and cannot excrete the toxins introduced through the placenta. Therefore, pregnant women with fever should seek medical attention in time to identify the cause and then treat it to avoid harm to the fetus.