Scientists Uncover Likely Cause of Stretch Marks

Applying moisturizer on belly

If you’re anything like the billions of women who have given birth or had their weight yo-yo at some point in their life, you’re probably pretty familiar with stretch marks. But in spite of its near universality, little is known about where they come from and why they don’t go away. Now a team of researchers has finally figured out some of the mystery in a paper published this week. Their findings might lead to better treatments in the future to help the skin recover after sudden episodes of rapid expansion.

Who gets stretch marks?

It’s thought that stretch marks occur any time the skin is forced to expand faster than it’s able to simply by stretching (the quick response) or by growing new skin (the very slow response). Some examples of people in this situation are: pregnant women, those rapidly losing or gaining weight, or children or teens going through a growth spurt. It’s clear that the skin of stretch marks is different from normal skin. What wasn’t known was exactly how it was different from normal skin that caused it to look and act so differently. This is where this research paper comes in.

How did the researchers study stretch marks?

The researchers wanted to understand on a microscopic level what was different about the skin of stretch marks compared to normal skin. To do this, they took skin samples from 27 healthy women. From these samples, 18 women had a family member who had stretch marks from pregnancy, 11 had been pregnant, and seven had stretch marks from pregnancy. They took these samples and stained them with special dyes to look at how fibers like collagen and elastin were structured in normal versus stretch-marked skin. They also removed genetic material from the different samples and analyzed this DNA to see if there was a difference in the types of proteins the cells in each sample was making and to find out if there might be a genetic basis for why some people get stretch marks while others don’t.

What did they learn about stretch marks?

The team found that the major difference between skin from stretch marks and normal skin is the way the elastic fibers are arranged. In skin from stretch marks, the fibers were thinner and far more disorganized. Rather than having strong, horizontal fibers in the lower layer and delicate, vertical fibers in the upper layer, stretch marks had fibers that were of all different sizes and pointed in all different directions. When the team looked at which genes were being used in the stretch marks compared to the normal skin, they found out production of elastin fibers had been ramped up dramatically, but that production wasn’t being coordinated between different areas of the skin. The researchers think that when the skin stretches beyond its capacity to stretch, the normal organization of elastic fibers gets pulled apart and broken up faster than the body can repair them. The body then seems to try to ramp up the creation of new elastic fibers, but the organized foundation it would normally lay them down on has already been destroyed. Since these fibers don’t work as well as usual, they slowly stretch out over time and can’t rebound back. That’s why the skin of stretch marks tends to get loose and saggy over time.

Are stretch marks genetically determined?

In a recent analysis of the genomes of people with and without stretch marks, researchers found a single change in the gene that codes for one of the building blocks of elastin fibers in some of the people with stretch marks. The team thinks that people with certain genetic changes may naturally have fewer or more disorganized elastic fibers in the skin to start out with. That makes their skin less able to stretch normally when a significant pull occurs, which makes them more likely to end up with stretch marks.

What does this mean for me?

This study is the first to really start to understand why stretch marks occur. The researchers hope their findings will help other researchers and physicians find new ways to treat or even prevent stretch marks from happening. Importantly, that also means that the many creams and lotions claiming to prevent or heal stretch marks aren’t actually basing those claims on any scientific research since this study is the first to understand what the problem is. You should think twice before spending your money on a cream that might be making promises it can’t keep about healing your stretch marks.