At 21 weeks of pregnancy, the fetal heart is usually located on both sides of the navel, but may also be a little to the left or right. At 21 weeks of pregnancy, the position of the fetal heart is not particularly fixed, this is mainly because at 21 weeks of pregnancy, the fetus is still relatively small, the range of intrauterine activities is relatively large, the fetus in the abdomen can be moved at any time, so listening to the position of the fetal heart changes is a normal phenomenon. In most cases, the position of the fetus is on both sides of the navel, but also may be a little to the left or a little to the right, at this time to hear the fetal heart can be, because the development of the fetal heart is not yet perfect, its regularity has not yet been formed, at this time, as long as the fetal heart can be heard, there is no need to worry too much.