Fetal heart and fetal buds appear gradually as the weeks of pregnancy increase. Generally speaking, the fetal heart is possible when the length of the bud is between 5-20mm. A 5mm bud is more than six weeks of pregnancy, while a 20mm bud is more than nine weeks of pregnancy, and the fetal heart appears between six and nine weeks, so it is possible to have a fetal heart within this time frame. If the fetal heart is still not visible even though the buds are over 20mm, the possibility of embryonic arrest is very high in this case. Usually during embryonic development, usually 3-4 weeks of pregnancy is also known as the period of germination, and the sac will be formed at 30-40 days of pregnancy, and around 40-50 days of pregnancy, the fetal bud will be formed, and around 50-60 days of pregnancy, the fetal heart will be formed, while the fetal bud is about 0.5cm-1cm, which is shaped like a small seahorse. If the pregnancy is around 6 weeks, the fetus mostly grows to 0.85cm, the organs of the fetus have been differentiated at this stage, and the fetal sac can also be clearly seen in the ultrasound, and the fetal buds and the fetal heart can be seen. If the pregnancy is about 7 weeks, the fetus can normally grow to 1.33cm, and the fetus has basically taken on the shape of a human being, with all the body segments differentiated, the limbs also differentiated, and the various systems of the body further developing. At this stage, the fetal buds and fetal heart can also be clearly seen in the ultrasound, while the fetal sac occupies 1/3 of the uterine cavity. Pregnant women are advised to take regular pregnancy tests to detect the fetal sac, buds and heart under the guidance of their doctors according to their own conditions.