Jay-b - unfortunately, there is nothing you can do to prevent stretchmarks. Like Fi said, if you are genetically pre-disposed to them, you are going to get them. Pregnancy will bring them on as your skin stretches.
They go red because as the skin stretches, it actually tears (there's more technical jargon for this but this is my basic understanding). They will fade over time and keeping moisture up to them will help them to fade faster but there is no cream in this world that will stop them or prevent them.
I guess it's just something that we need to accept. Unfortunately it is not talked about enough in society so when people see them, they freak out. They are normal and natural. People who don't get them are extremely lucky.