Why do strechmarks occur?

Stretchmarks occur because your skin was once bigger than it is now. Usually they occur after pregnancy, but can also occur after a successful diet. Skin loses its elasticity as we get older, so a pregnant 19 year old is more likely to lose the stretchmarks than a 48 year old who has just dropped 70 pounds after stomach stapling surgery.

They can also occur as a symptom to hormonal imbalance.

I advise a visit to a cosmetic dermatologist to establish that they are indeed stretchmarks and not something else, and ask about whether laser surgery could help.