I was at a birth class last night and this is what I learnt about Strep B:
* it can come and go in a few weeks (as someone already mentioned)
* having antibiotics does NOT ensure the strep isn't passed on to baby- ie babies can get the infection even if you are having an AB drip during labour
*many people choose not to have the test which is fine- the hospital assumes you are negative and they watch for baby listlessness after birth in ALL babies and from the APGAR score check also. If they are concerned, they give bub antibiotics.
* the main hospital here doesn't induce Strep B straight away- they allow 6 hours for labour to start naturally if your water break
Having said all that and like Samantha says, the chance of baby getting it from you and/or baby getting very sick is a tiny chance.