Causes of Stretch marks

Health encyclopaedia - Alphabetical Topic List

| A |

| B |

| C |

| D |

| E |

| F |

| G |

| H |

| I |

| J |

| K |

| L |

| M |

| N |

| O |

| P |

| Q |

| R |

| S |

| T |

| U |

| V |

| W |

| X |

| Y |

Stretch marks occur when the skin is stretched suddenly. The outer layer of skin isnâ€™t affected, but the dermis becomes thinner and develops tiny tears. The blood vessels that lie under the skin show through, giving the marks a reddish colour. Later, when the blood vessels contract, the purplish colour fades to silvery white.

Stretch marks appear most often in the following cases:

Pregnancy: Between 75 and 90% of women develop stretch marks during pregnancy. As you put on weight, the abdomen (stomach) is gradually stretched further and further, usually causing stretch marks to appear in the sixth or seventh month. Stretch marks can also appear on the thighs, and on the breasts as they get bigger and heavier.
Adolescent growth spurt: Boys and girls tend to grow very quickly during puberty. Boys often get stretch marks on the shoulders, and girls get them on the hips, thighs, and breasts.
Athletes: Athletes who train their muscles to get bigger and stronger over a short period of time sometimes get stretch marks. This is particularly common in bodybuilders.
Weight loss or gain: Putting on a lot of weight over a short period of time can cause stretch marks to form. If you are constantly on and off diets, stretch marks can also form, as your weight goes up and down rapidly. If you are dieting, it is important to lose weight slowly so that strain isnâ€™t put on the skin.

However, not everyone gets stretch marks. Doctors think some people get stretch marks because their bodies produce more of the hormone, corticosteroid, than normal. This hormone decreases the amount of collagen in the skin. Collagen is a type of protein in the fibres of the skin that keeps it stretchy.

Occasionally, stretch marks can be a symptom of Cushingâ€™s syndrome, a condition caused by too many steroid hormones. For more information, please see the separate encyclopaedia entry on Cushingâ€™s syndrome.