The primary objective is to compare the diagnostic accuracy of commercially available real-time polymerase chain reaction (PCR) tests and antenatal culture tests for diagnosing group B Streptococcus (GBS) colonisation in pregnant women during labour.

To investigate potential sources of heterogeneity in the diagnostic accuracy of the real-time PCR tests and antenatal culture tests. This will include variations in: type of intrapartum culture reference standard used, prevalence rate, and high or low GBS risk population.