I used bio oil, stretch mark cream and cocoa butter almost every night after I showered and still got stretch marks,... there isn't really alot to completely avoid them, but keeping your skin hydrated can help with the appearance.
Stretch marks are caused by your skins elasticity... Which is genetic. But keeping hydrated will help A LOT and find a lotion/oil/cream and use it everyday if not twice a day. If you get itchy don't scratch! Put lotion on. I use bio oil (kinda expensive) but it's recommended by lots of people and I love it.
Seriously drink a bunch of water, and OIL your tummy twice a day.
Ive used a moisturizing lotion and it seems to be working as im 8mths pregnant and don't have any strech marks as all