There are vitamins you can take that strengthen the membranes, and also vitamin c for prevention of infection if membranes do rupture. I would try looking in the gentlebirth.org archives to see if you could find what vitamins do stengthen the membranes. I think that is where I saw it. With GBS its hard to say but you can definately do alot of things like garlic internally, yogurt with active cultures, anything to establish good gut flora will help you.