What causes stretch marks?

New study questions the effectiveness of current topical treatments

A new study, published in the British Journal of Dermatology, has examined the causes of stretch marks at a molecular level and concluded that existing topical treatments have limited preventative effect.

Frank Wang MD, Assistant Professor and dermatologist at the University of Michigan Health System, lead the study’s team. He explained: “Most of the existing products aren’t based on solid scientific research. Very few to none of the items touted to prevent or fix stretch marks really work.”

Wang has been studying stretch marks for more than eight years. He says that this area of study hasn’t received much attention as stretchmarks are not viewed as being medically dangerous. But he believes its an area of research that deserves more attention because of the phycological effect they can have. He explained: “Because stretch marks may compound the stress of the new motherhood for many women, it’s important to learn more about them. Some women feel like their self-esteem, quality of life and willingness to engage in certain activities are affected.”

Stretched skin near the stretch mark (left, Perilesional) vs. stretch mark skin (right, Striae). Credit: U-M Health System

The team took skin samples from 27 pregnant women who had recently-formed stretch marks, comparing the marked skin to both nearby stretched skin on the abdomen and less-stretched skin on the hip.

Wang and his colleagues discovered that the elastic fibre in the dermis was disrupted in the marked areas. This remains disrupted even after pregnancy. The skin attempts to mend the elastic fibres, which usually give the skin its ability to “snap back”, afterwards. But not only is the repair ineffective, it also promotes the lax, loose skin often seen in more mature stretch marks.

The team looked at existing research of topical treatment options and did not find anything currently available that could effectively repair those disrupted elastic fibres. Wang said: “It may make more sense to focus on preserving the elastic fibres you have, rather than repairing damaged ones within stretch marks. Regardless, it’s more complicated than just rubbing something on your stomach.”

Wang is continuing his research into stretch marks with a focus on changes in collagen levels in the skin. He is also concluding a survey study of 200 pregnant women to better understand the impact of stretch marks on quality of life.

Stretch marks, or striae gravidarum, affect 50-90% of women at some point in their lives, although certain demographics are at higher risk than others. Family history, weight gain in pregnancy, multiple births and obesity can all have am impact on a woman’s likelihood of developing them.