Degree Name

Master of Midwifery - Research


School of Nursing


Aim The aim of this study was to complete a pilot project to ascertain if the research design was appropriate to determine whether a daily oral dose of probiotics can reduce the rate of vaginal group B streptococcal (GBS) colonisation in pregnancy.

Methodology A pilot randomised controlled trial was performed which recruited 34 GBS-positive women who were approximately 36 weeks pregnant. The participants were randomly allocated to the control group, who continued with standard antenatal care, or to the intervention group, which continued with standard antenatal care and received a daily oral dose of probiotics for three weeks or until the birth of their infant. A lower vaginal swab to detect the presence of GBS was collected three weeks post consent or when a participant was in labour.

Results 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 21 days of probiotics. A subgroup analysis, including only those who had completed 14 days or more of probiotics (n=16), also showed no significant difference in vaginal GBS when compared to the control. As a secondary finding of the analysis did show significantly more vaginal commensals in the probiotics group (p=0.048).

Discussion There are five possible reasons for the lack of significant results:

  • 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.
  • Oral probiotics are ineffective in impacting vaginal GBS.

Implications The secondary finding of a significant increase of vaginal commensals (normal vaginal flora, including Lactobacilli) in women who completed 14 days or more of probiotics supports the potential of probiotics to impact GBS in pregnancy. The presence of commensals should be included as an indicator in future research projects. This pilot project has provided no evidence that probiotic use in later pregnancy is unsafe. Many possibilities remain for future research to further investigate the use of probiotics to impact vaginal GBS.