Whether you have some or not, everyone knows what stretch marks (striae distensae) look like, and no one wants them. These skin marks are notorious among men and women alike. Women are more prone to develop them, though [1, 2]. Although they are entirely harmless, stretch marks are not considered particularly attractive.
The skin is our largest organ. The skin is very elastic and able to expand, thanks to the presence of elastic fibers. Stretch marks, however, often (not always) occur in skin that has expanded than what the elastic fibers can handle. Therefore, these marks often result from quick weight gain (whether it be due to an increase in muscle or fat mass), growth spurts, or pregnancy.
Stretch marks could be described as scars. Their structure is almost the same. They occur where the outer layers of the skin have atrophied, and the structure of the skin’s connective tissue is altered . Atrophy is the deterioration of tissue.
Upon initial formation, there is inflammation. During this phase, the marks are red, pink, or violet (striae rubrae). As time goes by, the marks become white (striae alba) [4, 5]. Where the lesions are, the elastin fibers are thinner and less than where the skin is normal [1, 5].
The exact mechanisms and causes are still an area of ongoing investigation. Interestingly, although there is a definite association, the stretching of the skin is not the only determining factor for stretch mark development [4, 5].
With pregnancy, for example, some women have a greater increase in their waist circumference without their skin showing any proof thereof. In other cases, ladies with less increase in their waist circumference experience striae .
Other than stretching skin that goes along with pregnancy and puberty, the accompanying hormonal changes are also closely related to the formation of stretch marks . Skin with stretch marks has been found to have double the estrogen compared to skin without these lesions . Androgen and glucocorticoid receptors have also been found to be increased.
Increased levels of corticosteroids significantly increase your risk - they are a significant contributing factor [1, 2]. Your adrenal glands produce corticosteroids. Conditions such as Cushing’s Disease cause high levels. Oral or injected drugs may also increase levels. These drugs are commonly used to counter acute inflammation.
The predisposition for the development of stretch marks  has also been associated with the ELN gene variants . ELN is the elastin gene. Elastin is responsible for the elasticity of the skin. Fewer elastin fibers may increase your likelihood of the development of stretch marks .
To summarise, the following are the known risk factors for the development of stretch marks [1, 4, 6, 8]:
- Family history (genes)
- Pregnancy (Younger age, Higher pre-pregnancy weight, Higher pre-delivery weight)
- Weight gain
- High levels of corticosteroids
- Increased numbers of estrogen, androgen and, glucocorticoid receptors
Treatment of stretch marks remains a challenge. For any treatment to improve the appearance and symptoms of stretch marks, it would need to target many factors. These factors include fibroblast activity for collagen production, elasticity, blood flow, cell proliferation, skin hydration, and inflammation .
May topical creams and ointments claim to help treat stretch marks. Topical treatments mostly contain ingredients aimed at increasing collagen production [1, 9]. More collagen should improve skin elasticity . Unfortunately, there is little convincing proof that topical treatments are effective [1, 9, 10].
Different types of laser therapies show the most promising results in improving the appearance of these scars [10,11].
Micropuncture/micro-needling (in conjunction with topical ascorbic acid) is a new technique that also seems effective by stimulating collagen and elastin production [12, 13]. However, for best results, treatment should be initiated while the marks are still pink in color [9, 13, 14].
In terms of prevention, more research is also still needed. Topical agents have not yet proven effective in preventing stretch marks . There is, however, some evidence that the application of creams with Centella asiatica extract and daily massage may help .
Everything considered the moral of the story is that hormones and genes may be to blame for your stretch marks. More so than the expansion of skin due to weight gain. So if you do have stretch marks, don’t blame yourself as it is not your fault.
Thus, if you got stretch marks, it’s not because you did anything wrong, so be kind to yourself, especially if you have a genetic predisposition that can be established by having your DNA tested.
 Lokhande, A., & Mysore, V. (2019). Striae distensae treatment review and update. Indian Dermatology Online Journal, 10(4), 380. https://doi.org/10.4103/idoj.IDOJ_336_18
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 Cho, S., Park, E., Lee, D., Li, K., & Chung, J. (2006). Clinical features and risk factors for striae distensae in Korean adolescents. Journal of the European Academy of Dermatology and Venereology, 20(9), 1108–1113. https://doi.org/10.1111/j.1468-3083.2006.01747.x
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