The stretch mark is crooked and related to fetal development, fetal position and right rotation of the uterus, as follows: 1, fetal development: as the pregnancy week increases, the fetus will gradually increase in size, the abdomen will gradually expand, the enlarged uterus will thin or separate the rectus abdominis muscle, pulling the stretch mark and shifting; 2, fetal position: most of the fetus is in head position, one side of the abdomen is the fetal limb, the other side is the fetal back, the limb side is low, the back side is high, both sides of the The uneven force on the rectus abdominis muscle will affect the travel of the gestational line, mainly seen in pregnant women who are thin and lack of exercise. In addition, women who have given birth repeatedly, especially in multiple births, will also experience a decrease in abdominal wall tension and a more pronounced separation of the rectus abdominis, resulting in a more skewed appearance of the gestational line; 3. Rightward rotation of the uterus: After pregnancy, the uterus will generally rotate to the right, and the rightward rotation of the uterus makes the abdomen uneven, resulting in a skewed gestational line. Stretch marks are mainly triggered by the gradual expansion of the abdomen, causing the elastic and collagen fibers of the skin to split. Stretch marks mostly appear from the fourth month of pregnancy and are not easily restored to their original state, especially when they become white atrophied scars as pregnancy progresses and are more difficult to eliminate completely. Therefore, you should reduce the risk of stretch marks arising during pregnancy by applying olive oil, paying attention to your diet, such as eating more fruits with vitamin E and vitamin B, including kiwi and grapefruit, and having proper massage. In addition, the skewness of the stretch marks is a normal phenomenon and pregnant women should not worry about it.