The line in the middle of a pregnant woman’s stomach is called the stretch mark, and the stretch mark becomes lighter in the fourth month of pregnancy, which is mostly a normal phenomenon. Stretch marks are mostly caused by melanin deposition. In the early stages of pregnancy, the increased levels of estrogen and progesterone in the pregnant woman’s body lead to abnormal metabolism of melanin cells, resulting in excessive deposition of melanin cells and the formation of stretch marks. With the prolongation of pregnancy, the level of various hormones in the pregnant woman’s body gradually tends to stabilize. At this time will accelerate the level of melanin metabolism, so that the stretch marks slowly become shallow; in addition, with the prolongation of pregnancy time, the fetus gradually grows, pregnant women’s abdominal circumference will also become larger and larger, the stretch marks on the belly will also become shallow. Pregnancy 4 months stretch marks become shallow for most of the normal phenomenon, no need to deal with. Because the pregnancy line will be affected by the pregnancy time, the body’s hormone level and other factors, the pregnancy line becomes shallow is mostly a normal phenomenon; if there are other discomforts, it is recommended to consult a doctor in time, so as not to delay the condition.