Paula Olsen, Moira Williamson, Victoria Traynor, Chris Georgiou

To perform a pilot project to determine if this research design was appropriate to explore potential causal relationships between oral probiotic use and vaginal Group B Streptococcal (GBS) colonisation rates in pregnant women. Thirty-four GBS-positive women at 36 weeks pregnant were recruited. The participants were randomly allocated to the control group, who received standard antenatal care, or to the intervention group, who received standard antenatal care and a daily oral dose of probiotics for three weeks or until they gave birth. A vaginal GBS swab was collected three weeks post consent or during labour. No significant difference was found in vaginal GBS rates between the control and intervention groups. Only seven of 21 women in the intervention group completed the entire 21days of probiotics. A subgroup analysis, including only those who had completed 14days or more of probiotics (n=16), also showed no significant difference in vaginal GBS when compared to the control. The findings did show significantly more vaginal commensals in the probiotics group (p=0.048). Five possible reasons for the lack of significant results are: the length of the intervention was too short; the dosage of the probiotics was too low; the wrong strains of probiotics were used; the sample size was inadequate; or oral probiotics are ineffective in impacting vaginal GBS. The finding of a significant increase of vaginal commensals in women who completed 14days or more of probiotics supports the potential of probiotics to impact vaginal GBS in pregnancy.