According to a study by Chang et al. (2004), the stretching is not the primary cause of stretch marks. Studies found that there is no correlation between the development of stretch marks and weight gain per week. There is also no correlation between the greater percentage increase of abdominal/hip circumference during pregnancy and a greater number of stretch marks.

Hormonal changes. Stretch marks develop in times of increased glucocorticoid production, for example during puberty, pregnancy, with Cushing’s syndrome or with external steroid use. High steroid hormone levels have a catabolic effect on the activity of fibroblasts and decrease the deposition of collagen in the ground substance of the dermal matrix. Clinical publications confirm that hormonal changes are one of the main reasons for stretch mark development. It is a defect in the basic structure of the elastic tissue. This theory was posted after a relationship was found between stretch marks and increased vaginal lacerations at birth. An extracellular matrix defect may also explain why overstretched tissue leads to ruptured collagen fibers and hence stretch marks in some individuals who experience rapid weight change e.g. during pregnancy or when suffering from Cushing’s syndrome. Mechanical stretching can lead to the rupture of the connective tissue framework during pregnancy, growth spurts in adolescence, obesity and rapid increase or decrease in weight.

Although they are not detrimental to health, they can cause physical symptoms such as itchiness, tenderness and pain. Because of their appearance, they can also significantly affect a person`s self-esteem and self-perception.