Generally speaking, you can lie flat after pregnancy, and it is recommended that you lie on your left side in the middle and late stages of pregnancy, but in a position that is comfortable for the pregnant woman herself. 14 weeks to 27 weeks of pregnancy is the middle stage of pregnancy, generally speaking, before 16 weeks, because the uterus increases in size is not obvious, the sleeping position will not cause any effect on the mother and the fetus. After 16 weeks, the growth and development of the fetus will gradually accelerate, and the size of the uterus increases more. If you sleep flat on your back at this time, it may increase the pressure of the uterus, which will compress the abdominal aorta and inferior vena cava, and easily cause supine position syndrome. In serious cases, it will also cause pregnant women to experience a drop in blood pressure, dyspnea, and at the same time, the blood supply to the placenta also has an impact on the growth and development of the fetus, so it is recommended to choose the left side of the lying position. However, this is not absolute, it needs to be based on the pregnant woman’s own physical condition and the results of the maternity test. Because many pregnant women after falling asleep, will not deliberately change the sleeping position, sometimes involuntarily will become flat. If there is no discomfort and the fetus is moving normally, you don’t need to worry about it, just keep the left side lying position when you are awake. Throughout the pregnancy, you need to pay attention to regular checkups, and if there are any abnormalities, then you need to consult a doctor in time.