Vitamin e helps, some lotions or oils have it. Its not always preventable, some women get it even with creams.
It's genetic. You can't prevent them. You can make them lighter with lotions, but can't prevent them. You either get them or you dont.
Try really hard to not gain too much weight too fast. Don't worry about "showing" it will happen. And yes genetics are a factor, stay moisturized.
Bio oil and cocoa butter lotion ;)
Bio oil is actually harmful. Try not to use that. I use cocoa butter