Stretch marks - Causes 

Causes of stretch marks 

Stretch marks occur when the skin is stretched extensively over a short time period.

The rapid stretching causes the middle layer of skin (dermis) to break in places, allowing the deeper skin layers to show through, forming stretch marks.

The dermis is made-up of strong, inter-connected fibres that enable your skin to stretch as your body grows.

If part of your body, such as your abdomen (tummy), grows rapidly over a short period, the fibres can become thin and over-stretched and some may break.

At the point where the skin fibres break, tiny tears develop which allow the blood vessels below to show through. This is why stretch marks are often red or purple when they first appear.

When the blood vessels eventually contract (shrink), the pale-coloured fat underneath your skin will be visible, and your stretch marks will change to a silvery-white colour.

When stretch marks occur

Stretch marks often occur in the following situations:

  • during pregnancy
  • after rapid weight gain
  • during puberty
  • if you have a family history of stretch marks
  • if you have an underlying health condition, such as Marfan syndrome
  • after the prolonged or inappropriate use of corticosteroid medication  

These are discussed in more detail below.

Pregnancy

Stretch marks are common during the later stages of pregnancy, affecting up to 80% of pregnant women. Whether or not you will get stretch marks depends on your skin type and how elastic it is.

During pregnancy, your body produces hormones that soften the ligaments in your pelvis so that they are more flexible when you give birth. Ligaments are strong bands of tissue that connect joints. However, the hormones also soften the fibres in your skin, making you prone to stretch marks.

As your baby grows, you may develop stretch marks on your abdomen (tummy) as your skin stretches. You may also develop stretch marks on your thighs and breasts as they get bigger.

After childbirth, most stretch marks will fade and become less noticeable, but they do not always disappear completely.

Rapid weight gain

You may get stretch marks if you put on a lot of weight over a short period of time.

In some cases, the stretch marks may remain, even if you lose the weight. However, they should fade over time.

If you diet regularly, stretch marks can develop as your weight goes up and down. If you need to lose weight, lose it slowly and steadily so your skin is not put under strain.

Read more about how to lose weight safely.

Bodybuilders and athletes can sometimes get stretch marks as their muscles increase in size.

Puberty

During puberty, the body often develops very quickly in growth spurts. As a result, males may get stretch marks on their shoulders and back, and females may get them on their hips, thighs and breasts.

Family history

If you have a close relative who has stretch marks, such as your mother, you are more likely to develop them yourself.

Although stretch marks can affect both male and female members of your family, they occur most often in women.

Underlying health conditions

Stretch marks can sometimes be caused by rare, underlying health conditions, such as Cushing's syndrome and Marfan syndrome.

Cushing's syndrome occurs when the body produces excess amounts of cortisol, the hormone that may make some people more prone to developing stretch marks than others.

If you have Cushing's syndrome, you may develop noticeable, dark coloured stretch marks. 

Marfan syndrome is caused by a faulty gene which affects your body's skin and connective tissues. It weakens your body's tissues and affects their elasticity (ability to stretch). This results in your skin not being as resistant to stretch marks as it should be.

If you have Marfan syndrome, you may develop stretch marks on your shoulders, hips or lower back.

Corticosteroids

In rare cases, stretch marks can develop after prolonged or inappropriate use of corticosteroid medicines, such as creams or lotions used to treat skin conditions, including eczema.

Corticosteroids work in a similar way to the hormone cortisol, which is naturally produced by your body.

Corticosteroids can help ease inflammatory skin conditions, but like cortisol, they can also decrease the amount of collagen in your skin.

Collagen is a protein that helps keep your skin stretchy. This means that the less collagen there is in your skin, the more likely you are to develop stretch marks.

When using a corticosteroid cream or lotion, make sure you follow the manufacturer's instructions regarding how and where to apply it. The face, groin and armpits are particularly sensitive areas. Ask your GP or pharmacist for advice if you are unsure.


Page last reviewed: 05/07/2012

Next review due: 05/07/2014

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