Hi Stretch marks occur especially on Areas where there is a rapid growth for example on Arms legs shoulders when you are growing up e.g.. growth spurt happens in the Teenage or on the abdomen on a pregnant lady. Some people might be more prone to stretch marks if it is running in the families. how to regulate stretch mark is basically to contain weight gain which is which can happen rapidly if you are eating lot of junk food or if you are exercising vigorously to treat stretch marks. usually doctors recommended retinol based cream which can be applied some of these are available as lotions as well and usually a combination of some treatment such as micro needle treatment or laser treatment is recommended to make them appear less prominent.