Clinicians need information on the risk of Early Onset Group B Streptococcal disease (EOGBS) for counselling pregnant women and to decide who would benefit most from antibiotic treatment during labour. We carried out a systematic review of the research literature and conducted meta-analyses to obtain estimates for the natural history of EOGBS that are representative of the UK population. The mean rate of colonisation for the UK was 14% and we found weak evidence that the prevalence is increasing over time. Maternal GBS colonisation was more likely in women who delivered preterm compared with at term. Just over one-third of babies born to colonised mothers become colonised with GBS at birth (36%), and 3% of colonised babies develop EOGBS bacteraemia. In the UK, EOGBS constitutes one-third of all early onset bacteraemia due to pathogens, in contrast to one-half in the USA.