Sleeping on the right side can have different effects on the fetus depending on the stage of pregnancy, for example, it can cause fetal ischemia and hypoxia, intrauterine asphyxia, and lead to the formation of venous thrombosis in pregnant women. In the first 3 months of pregnancy, sleeping on the right side does not have a great impact on the fetus and the pregnant woman because the fetus and the uterus are too small. After the third month of pregnancy, especially in the late pregnancy, the uterus gradually increases in size and is mostly right-sided, so if you sleep on the right side again, it will compress the abdominal aorta, which will lead to poor blood circulation and affect the blood supply to the fetus, resulting in lack of blood and oxygen, and in severe cases, the fetus may be suffocated in utero. At the same time, sleeping on the right side will also compress the inferior vena cava of pregnant women, reducing blood circulation in the lower extremities and making them susceptible to venous thrombosis. Therefore, it is generally not recommended for pregnant women to sleep on the right side, and it is better to adopt the left-side lying position, which can offset the compression of blood vessels by the right rotation of the uterus and make the blood flow in the uterus, which is beneficial to the growth and development of the fetus; at the same time, for pregnant women, gestational hypertension can be avoided to a certain extent in the middle and late stages of pregnancy. If you take a left-sided position and rest for too long, thus feeling too tired, you can also occasionally take a moment of rest in the right-sided position. Pregnant women should pay attention to the combination of work and rest, do not sit still for a long time, and should not be overworked.