Stretch marks are striations on the outermost layer of the skin due to the ruptured and damaged collagen and elastic fibers underneath. The primary reason of irritated and torn collagen and fibers is excessive stretching of the skin beyond its normal capacity.

Different Causes of Stretch Marks:

* Increased Production of Cortisol:

Cortisol is an adrenal-cortex hormone that is active in carbohydrate and protein metabolism. This hormone makes other people more vulnerable in getting stretch marks.

* Pregnancy:

Blame it to the expanding belly, and thickening hips and thighs, stretch marks are common to pregnant women. Some women experience stretch marks as early as on their sixth month while some never experienced it even after giving birth.

* Weight Gain

Apart from fluctuations of the hormones glucocorticoids in the bloodstream, your body parts increase in size when you gain extra weight, thus stretching your skin.

* Obesity

Obesity is considered to be more than average fatness. In here, your skin is stretched more than its limit. Thus, tearing your elastic fibers and supportive collagen located in your dermis, and spreading your epidermis think and weary.

* Muscle Growth

Body builders get stretch marks, but they are not fat, why is that? Because of the more than average muscle growth, skin is stretched, and fibers under the skin are torn.

* Puberty

This is the period of growth spurt where body parts of adolescent boys and girls expand and grow in size or thickness. Usually, boys get stretch marks on their back and shoulders, whereas girls tend to get stretch marks on their breasts, thighs and hips.

* Genetics

Stretch marks can be inherited from grandparents and parents. If your close relatives have stretch marks, chances are your cells contain the same genetic makeup featuring the displeasing stretch marks.

* Overuse of Corticosteroids Skin Creams

These creams help to provide relief from inflammatory dermal conditions, but it can also decrease the amount of collagen from the skin. The least amount of collagen present in your skin, the higher the likelihood of stretch mark development.

* Marfan Syndrome

Marfan syndrome affects the elasticity of your skin through weakened connective tissues. When you are afflicted with Marfan syndrome, your skin is not as tolerant to expansions.

* Cushing's Syndrome

When your body produces excessive amounts of cortisol, Cushing 's syndrome occurs. Cortisol, just like corticosteroids, is the hormone that increases the probability of gaining stretch marks.

* Bad Diet and Water Intake

A lifestyle of inadequate water intake, and excessive salt, sugar and food preservative consumption will likely lead you closer to stretch marks.

Please see the link below to know more about Stretch Marks in details.

Source: http://www.consumerhealthdigest.com/stretch-marks/causes-of-stretch-marks.html