You won’t automatically get stretch marks, however, odds are you probably will; approximately 9 out of 10 pregnant women do! The good news is that they won’t all be massive, red, scary, and they will fade in time.

Stretch marks are still heavily misunderstood and dermatologists are still learning what causes stretch marks. There are many factors thought to contribute towards stretch marks and it’s thought to be any one or any combination of the following: weight gain, hormones and genetics.

There are also illnesses such as Cushing’s syndrome (causes hormones to be overproduced, which can weaken the skin), Marfan syndrome (weakens the skin due to a defective gene) and Ehlers-Danlos syndrome or EDS (affects the proteins in the skin, making it vulnerable to stretching)

Other factors that contribute to the elasticity of the skin can also impact the appearance of stretch marks, such as hydration and diet.

According to Frank Wang, M.D., assistant professor and dermatologist at the University of Michigan Health System, “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.” For more info have a look here

There is also a study looking to assess the effectiveness of topical treatments for preventing stretch marks. After including 6 trails and involving 800 women they concluded, “We found no high‐quality evidence to support the use of any of the topical preparations in the prevention of stretch marks during pregnancy.” They do, however, conclude that there is a need for more trails of higher quality and larger sample sizes.

http://www.ncbi.nlm.nih.gov/pubmed/26179468