The four-dimensional ultrasound examination, the fetus without abnormalities in the case of a one-time pass, to choose the appropriate examination time, eat before the examination, appropriate exercise, maintain a good state of mind. 1. Appropriate examination time: it is recommended to go to the hospital to do four-dimensional ultrasound examination in 22~28 weeks of pregnancy, the development of the fetus is too small and imperfect in all aspects will affect the results of the examination, the fetus is too large in the uterus, the range of motion becomes smaller will also affect the results of the examination. 2. Eating before the examination: eat properly before the four-dimensional ultrasound examination, do not go to the examination on an empty stomach, after a full meal the fetus in the uterus to absorb nutrients in the uterus, in the uterine cavity of the mobility of the larger, is conducive to passing the examination. 3. Appropriate exercise: do four-dimensional color ultrasound examination before appropriate exercise can walk climb, stairs, prompting the fetus in the uterus to move up, do four-dimensional color ultrasound is easy to one-time pass. 4. maintain a good state of mind: do four-dimensional ultrasound before to adjust the individual’s state of mind, try to maintain a pleasant mood, conducive to the fetus in the uterus to increase fetal movement, do four-dimensional ultrasound a one-time through the odds than larger. It is recommended to go to a regular hospital to do four-dimensional ultrasound examination, there are abnormalities to further examination and judgment.