Vaginal swab during pregnancy

Did anyone went or was told to do a vaginal swab to check on bacteria in the vagina before? Did you went ahead with it or did you not? I was told by my gynea to come down for the swab which was yesterday (didnt need to for my firstborn) but i didnt turn up cause i was feeling so tired and giddy. Im alrdy almost at my 9 months. This swab was told that if there's a bacteria they will give me an antibiotic so that the baby wont contacted with the bacteria during give birth.