The vagina is colonised by a dynamic community of bacteria, viruses and fungi, collectively termed the ‘microbiome’. In this talk I will describe how vaginal microbiome compositions can modulate host immune and inflammatory responses implicated in key stages of pregnancy, including parturition and labour. I will also present recent findings from our laboratory demonstrating how different vaginal bacteria target glycan structures throughout the reproductive tract to modulate colonisation dynamics and host immune responses. Finally, results from recent studies using live vaginal biotherapeutics designed to modulate the microbiome to improve pregnancy outcomes will be shared.