I asked my midwife about this yesterday and they said they test if it's in your urine at booking in and if it is you'll be told and they'll monitor/treat accordingly. Apparently if it's in your urine (rather than a swab) the chances are higher of it being passed on but otherwise the risk is very low. WHO don't recommend testing in pregnancy as its a transient virus which comes and goes so people would be given antibiotics unnecessarily. The USA test all pregnant women and their rates are no better than the UK so this also points to the ineffectiveness of testing. She did say the NHS are very hot on any sign of infection so if you or baby showed any signs of infection eg temperature you would be given antibiotics. I am a worrier and have stressed about this on numerous occasions but she did put my mind at rest. Hope this helps xx