There is no prevention for strechmarks!! They just reduce the apperance just like baby-love says
Coconut oil and sweet almond oil. It's natural and full of nutrients very good for your skin. The idea is to increase the skin's elasticity as much as you can. Look into improving skin elasticity. I used Palmers religiously (3-5 times a day) for the first 3-4 months. I don't know if it has made any difference.. I stopped using it because I now try my best to use more natural unprocessed things for my skin. Also lotions with petroleums I avoid. I get my "homemade" natural lotion and body creams from PDK Soaps. I got my organic coconut oil from Natural Grocers.. the coconut oil from Walmart is blehh.
Vitamin E oil helps keep your skin moisturized and less itchy
Scratching doesn't cause them its your skin stretching and part of pregnancy some women get them some don't, Stretch marks are caused by changes in the elastic supportive tissue that lies just beneath the skin, also genetic.but you can't prevent them but you can lighted them up with lotions made for stretch marks
Gain weight very slow and steady.
You can't prevent them, but to help reduce appearance you can use cocoa butter, bio oil, coconut oil, and vitamin e.