Fetal movement on the left side is not necessarily a son, nor is there any scientific basis for it. The sex of the fetus is generally dependent on the male chromosome. Fetal movement on the left side usually indicates that the fetus’ limb is on the left side and the back is on the right side, because the fetal movement on the limb side is more obvious. Theoretically, fetal movement can be in any part of the uterus, and the location of the fetal movement is related to the fetal position, so it cannot be based on the fact that the fetal movement on the left side is suspected or inferred to be a son. In addition, the sex of the fetus is determined at the moment of the formation of the fertilized egg, and depends mainly on the male chromosome. When a sperm with a Y chromosome combines with an egg, it develops into a boy, and if a sperm with an X chromosome combines with an egg, it develops into a girl. During pregnancy, pregnant women should never believe in any folklore to determine the sex of the child. Whether it is a boy or a girl, as long as the fetus develops healthily is the best. It is important to note that pregnant women should undergo regular checkups and seek prompt medical attention for any uncomfortable symptoms.