Invasive group B streptococcus (GBS) disease is a leading cause of neonatal death. There is no UK national screening programme for GBS in pregnancy, hence colonisation rates are unknown. Intrapartum antibiotic prophylaxis is given during labour to colonised women to reduce neonatal GBS transmission and subsequent invasive infection. Data about prevalence of other haemolytic streptococci in pregnancy, including group A streptococcus (GAS), are uncommon despite increasing importance. This study investigated colonisation in 100 pregnant women using conventional culture methods; 19% had GBS. This suggests that GBS carriage is common in the UK. The role of other β-haemolytic streptococci remains undefined.