I tested positive before due date and was given IV antibiotics during birth so it wasn’t passed onto my child. They also kept us in a little longer than usual and did monitoring before we could go home. I’m not sure if you ask for the test but they found I had it, I think K may have had a swab when I has a membrane sweep. Sorry I don’t know more.
It varies from area to area I think. With my first pregnancy (NW London) I had the swab at about 34 weeks as they were a pilot area and tested everyone for it. This time round it was apparently detected in a urine sample at around 12 weeks. It was all very odd, they didn’t say it was Group B Strep at first, just said they’d detected an infection and wanted me to redo the urine test as the chances were it was just a contaminated sample. So, I redid the sample a week later and gave it to the GP’s reception, not knowing exactly what it was I should have been asking for, and GBS must not be one of the things they routinely test for there, as they didn’t say anything had been picked up, so I assumed the first sample was iffy or the infection had passed. It was only another 2 weeks later when I gave a pee sample at the hospital again that a midwife said I still had an infection, asked whether I’d had antibiotics for it from the previous urine test and finally mentioned it was GBS. No idea why she was so coy about saying exactly what it was. Does it panic some women or something? Very odd. Anyway, I was given a prescription for the antibiotics and will be on an IV drip during labour again. No big deal....
The NHS don't test for it because (1) if you test negative, you can still catch it between testing and labour, so no point (2) even if you have it (and it's fairly common), it's very unlikely you'll pass it to baby and (3) IVF anti-biotics haven't been shown to be particularly effective at preventing transmission (and in fact, just makes anti-biotic resistance more common).
NICE guidance is to monitor baby closely for signs of infection as a more appropriate way of dealing with risk of infection
I asked to be tested just before I was due. It's not standard where I was and was told it would cost about £30 but in the end I didn't have to pay anything. It's not guaranteed because you can develop it at any time but it out my mind at ease. I ended up on an antibiotic drip anyway during labour so it wasn't a worry after but definitely ask if you're worried.