This study was conducted to find out the group B streptococcus colonisation of pregnant women in Kocaeli, Turkey. A culture plus individualised high-risk-based antibiotic prophylaxis was compared with high-risk-based approach alone. The screening of women was performed via vaginal and anal cultures for group B streptococcus (GBS). The maternal GBS colonisation rate was found to be 6.5%. All colonised women or preterm labours; with unavailable culture results until delivery received prophylactic antibiotics. Neonatal colonisation rate and early-onset neonatal sepsis due to GBS was 1/200. The unscreened 900 women received prophylactic antibiotics due to a risk factor-based approach. The neonatal colonisation rate was 17/900 (p = 0.1), and the rate of early-onset neonatal sepsis was 3/900 (p = 0.6). A culture plus individualised high-risk-based antibiotic prophylaxis provided an insignificant change in neonatal colonisation and early-onset neonatal sepsis with GBS when compared with high-risk-based approach alone.