The vast majority of pregnant women will not have a fetal heart in the 5th week of pregnancy, and the fetal heart will appear gradually in about 6~7 weeks. At 5 weeks of pregnancy, the gestation time is still relatively short, the development of the fetus is not complete, and the fetal heart is not seen through ultrasound; however, at this time, the fetus has primitive cardiovascular pulsation, and the length of the fetus is about 0.4 CM, and the fetal sac accounts for less than 1/4 of the volume of the uterine cavity, as can be seen from the ultrasound. At 5 weeks of gestation, the vital organs of the fetus begin to develop, such as the kidneys and liver, and the neural tube begins to develop gradually. This is followed by the growth of nails, hair and sweat glands, all of which can be detected by ultrasound. At 5 weeks of pregnancy, pregnant women should go to the hospital for regular checkups to understand the development of the embryo, and if the fetal heartbeat is not seen at 6 to 7 weeks, attention should be paid to it.