What Causes Stretch Marks?

Let’s talk about stretch marks. Nobody wants them, but many people get these reminders that while the skin is an amazingly elastic and durable organ, it, unfortunately, has its limits. Stretch marks form as a result of your skin suddenly stretching, and while both men and women get them, they’re more common in women.

To that end, most people associate stretch marks with women having gotten pregnant. And that is absolutely a major cause of stretch marks – more than 70 percent of women are believed to get stretch marks starting around the 25th week of their pregnancies – but it is far from the only one. After all, how could it be if men get them too? In fact, it’s amazingly common for stretch marks to form on both boys and girls as they experience growth spurts while going through puberty. According to Medical News Today, around 40 percent of boys and about 70 percent of girls get stretch marks while going through puberty.

If that number seems impossibly high, there are two things you should keep in mind. First, stretch marks can range from very large and purple or red in color to very small and silvery-white in color, meaning some are far less noticeable than others. Second, young people’s bodies heal better than older people’s, so it’s common for stretch marks formed during puberty to heal to the point of being barely visible anymore.

What Are Stretch Marks?

Before we go any further, let’s back up for a second and properly explain what stretch marks are. Medically, stretch marks are called striae distensae, SD, striae, striae atrophicans, and striae gravidarum. These dermal scars are linear, smooth bands or narrow streaks that become visible on the skin as a result of the sudden stretching we talked about.

There is no medical danger in having stretch marks – they’re completely harmless, so the good news is that if you get some, there is nothing more serious to worry about. However, many people are uncomfortable with the look of them on their bodies, and they can cause emotional or psychological distress.

What Causes Stretch Marks?

Now that you know what they are, let’s talk about how and why you get them. Most people think of their skin as their epidermis, but that’s actually only the outer layer of your skin. Beneath that is the dermis and then beneath that is the hypodermis. Stretch marks form at the dermal level after connective tissue is stretched beyond its elastic limits when the skin is rapidly expanded or contracted from sudden weight loss or gain. Yes, weight loss can cause them in addition to weight gain, so even when you experience a big win by losing significant weight, you can still get stuck with stretch marks as a result. Bummer.

When the skin is stretched too far in any direction too quickly it causes tears and skin below the surface level may show through. While it’s true that everyone’s body experiences changes in size/weight – up and down – as they go through the normal aging process, it’s only rapid changes that cause stretch marks. The skin has amazingly strong fibers, but their elasticity does have limits and can be stretched too far and break.

The initial red or purple hue of stretch marks fades over time because blood vessels eventually contract and the pale fat – everyone has some, so don’t panic – beneath the skin becomes visible.

Now, let’s take a deeper dive into some of the most common causes of stretch marks.


As mentioned, stretch marks are likely to form during the latter stages of pregnancy, though this is dependent on a woman’s skin type and elasticity. When they do form, stretch marks usually show up on the abdomen as the baby grows and stretches the skin there, but they’re not always confined to just the stomach – pregnant women can also form stretch marks on their thighs and breasts.


Boys and girls go through rapid growth cycles during adolescence. Boys tend to get stretch marks on their shoulders and back during this time, while girls commonly get them on their hips, thighs, and breasts.

Rapid Weight Gain

It’s common to assume this just means people who gain a lot of fat, but while that can cause stretch marks, there’s more to this than just gaining fat. Athletes and bodybuilders who go through rapid muscle increases in short bursts can also form stretch marks.

Medical Conditions

Cushing’s syndrome, Marfan syndrome, and other medical conditions have also been linked to stretch marks. The former often leads to rapid weight gain because of cortisol overproduction, while the latter weakens the skin’s elasticity.

High BMI

Those with a high body mass index are more likely to form stretch marks than those with a lower body mass index. This is particularly common among women.

What can be done about stretch marks?

Aside from avoiding rapid weight changes and hoping you’re lucky enough to have good genes and a puberty and/or pregnancy that doesn’t cause stretch marks, what can you do about them? If you do get stretch marks, you don’t have to live with them. Laser stretch mark treatments like the ones offered at Park Slope Laser Aesthetic Center can be very effective at reducing them. Call us or request a consultation to learn more.

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