Pregnancy is a special physiological stage for women, and the changes of Qi and blood in the body can be reflected in time by the dynamic changes of pulse, which provides an important basis for clinical diagnosis and treatment. Pregnancy is a very complex and coordinated physiological process, in which the physiological changes related to pulse changes include: 1. Changes in blood pressure. Relatively speaking, in the middle trimester, the blood pressure is low; at the end of the pregnancy, the blood pressure increases slightly, the general systolic blood pressure does not change, the diastolic blood pressure decreases slightly due to peripheral vasodilation, hemodilution and placental arteriovenous short circuit, and the pulse pressure increases slightly. 2.The change of cardiac output. Cardiac output increases gradually from 8-10 weeks of gestation and reaches the peak at 32-34 weeks of pregnancy until delivery. 3.The change of blood volume. The maternal blood volume begins to increase from 6-8 weeks of pregnancy and reaches the peak at 32-34 weeks of pregnancy until delivery. The above physiological changes are closely related to the physiological function of Zang-fu organs, which leads to the change of slippery pulse. With the continuous development of modern pulsology, Professor Lucheng Song has been studying the knowledge of modern physics such as hemodynamics, hydrodynamics and acoustics based on his long-term clinical practice. By touching different levels of depth and the part of radial artery, it is found that the formation mechanism of pulse information, especially unsmooth pulse, is similar to the principle of sonar emission and reception: the heart is equivalent to the transmitting device of sonar wave. Each contraction of the heart produces a cluster of powerful sound waves, which are rapidly transmitted to the whole body along the arterial wall and the blood in it as a medium.More than 90% of the arterial blood flow of normal organs and tissues is a steady laminar flow, which does not produce turbulence, so there is abnormal vibration when a certain organ and tissue has pathological changes. The arterial blood flow is squeezed and deformed which causing turbulence and produces abnormal vibrations, which are fused with a larger cluster of sound waves transmitted by the heart and then transmitted to the whole body. The investigators can feel this kind of sound waves which combine abnormal vibration waves by touching different levels of arteries close to the body surface, including the radial artery. At the same time, Professor Lucheng Song's team has conducted in-depth research on the characteristic unsmooth pulse of stable coronary heart disease, liver cirrhosis, gastritis and other diseases.Different pulse sound waves were collected by using Pulse Detection System of Sound Waves(PDSSW),and ideal results were obtained through analysis. During pregnancy, due to the significant increase in blood flow and maternal changes,the shape of sound waves transmitted to the radial artery in the artery will be changed. Professor Lucheng Song found in clinical practice that the pregnant pulse will have different sensations of smoothness and penetration in different parts of the finger, by touching different levels of depth and the part of the radial artery. It was found that the pulse condition of normal pregnant women in the middle and third trimester of pregnancy was different from that of normal non-pregnant women in different level and part of radial artery.Based on the above analysis, this study will use PDSSW to collect the pulse waves of 76 the Middle and Third Trimester of Pregnancy and 76 relatively healthy women.Fourier transform, wavelet analysis, Hilbert-Huang transform and other methods will be used to identify the different characteristics of the sound wave signals, and observe the time-frequency domain characteristics of the trial group and the control group. Then diagnostic tests will be performed to calculate the sensitivity and specificity of PDSSW in the diagnosis of the middle and third trimester of pregnancy women.This trial will further verify the effectiveness of pulse diagnosis and lay a foundation for the diagnosis of complication of pregnancy by pulse diagnosis instruments.