Do probiotics in pregnancy reduce the risk of group B streptococcal colonisation?

Rectovaginal group B streptococcal (GBS) colonisation affects approximately 30% of pregnant women, which significantly increases the use of antibiotics in mothers and babies. In this review, we aim to answer two questions: (i) In pregnant women, does the use of probiotics prevent GBS colonisation prior to delivery when compared with placebo; and (ii) In GBS positive pregnant women, does the use of probiotics reduce the risk of GBS colonisation prior to delivery when compared with standard treatment. Pubmed, Cochrane library, EMBASE, OVID, clinical trials.gov, grey literature and conference proceedings were systematically searched to identify eligible trials. References of included trials were also reviewed. A total of four studies (n= 402) were included in the final review. Two studies reported on the prevention of GBS colonisation in healthy pregnant women, and two studies reported on the rate of GBS clearance after probiotic administration. Meta-analysis of the two studies using random effects model indicated that GBS clearance with probiotics was not statistically significant with odds ratio 2.12 (95% confidence interval 0.60-7.50,P= 0.17). Collection of adverse events data was not a primary or secondary aim in any of the studies. We conclude that there is limited evidence to recommend the regular use of probiotics to minimise the risk of GBS colonisation. Results from ongoing studies are likely to add to the current existing evidence.