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Science Behind Stretch Marks

Stretch marks, also known as striae in dermatology, are defects of the skin that occur in the uppermost layer of the skin. They typically look like lines of discoloration in the superficial layers of the skin, the dermis. Since these marks can be prominent, they represent one of the most disconcerting skin conditions for many people.


In reality, however, the stretch marks aren’t really pathological; they are more cosmetic. The stretch marks are caused by tearing of the superficial layers of the skin. However, for stretch marks to occur, the forces causing the tearing have to act relatively rapidly.


Following the tearing of the skin, the body’s reparative process tries to heal the defects through scarring and fibrosis. Unfortunately, the healing results in deposition of tissue that is a different color from the rest of the skin, causing these marks.

As one would expect, the stretch marks therefore occur during periods when the skin is subjected to too much tension. The commonest instance of this is during pregnancy. In such a case, the presence of the growing fetus normally forces the skin to expand faster than it can do so comfortably, causing it to tear and repair itself during the process. This leads to formation of the stretch marks.

Apart from that, the presence of stretch marks during pregnancy can also be attributed to formation of estrogens. Estrogen is a female hormone formed and escalated in formation during pregnancy and the teenage years.


It causes redistribution of fat all round the body to give women their characteristic shape. One of the most common sites of redistribution is to the breasts, and this is why stretch marks also occur on the breasts.

As it has been mentioned earlier, stretch marks can also occur during puberty. This is normally the result of hormones produced during puberty. These cause a rapid growth spurt in both boys and girls, and in some instances, it may cause the skin to stretch much faster than it should.


In girls, the rapid redistribution of fat to areas such as the hips and breasts has an effect of increasing the formation of stretch marks, and this is why they are more common in girls than they are in boys.

In a nutshell, it’s easy to see why stretch marks form: they are the result of increased tension placed on the skin due to rapid growth or increased fat such as in pregnancy, the growth spurt in puberty and even when one gains too much weight too fast and vice versa.

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