I didn't have it, and when I asked my OB about it he wasn't a fan, simply because it doesn't reflect how you'll be when you go into labor. He offered me the opportunity to have it if I wanted, but said it wasn't necessary, so I didn't have it. However, I had a hind water leak at 40 weeks and was given 4 days to go into labor naturally before being induced. I was put on antibiotics as a precaution and no GBS swab was taken. However, I think if your waters have broken, bubs is susceptible to other types of infection other than GBS, so they give you the AB's anyway.