Secretor status is a modifier of vaginal microbiota-associated preterm birth risk.

Mutations in the gene that result in a lack of expression of histo-blood group antigens on secreted glycoproteins may shape the vaginal microbiota with consequences for birth outcome. To test this, we analysed the relationship between secretor status, vaginal microbiota and gestational length in an ethnically diverse cohort of 302 pregnant women, including 82 who delivered preterm. and were found to have distinct co-occurrence patterns with other microbial taxa in non-secretors. Moreover, non-secretors with spp. depleted high diversity vaginal microbiota in early pregnancy had significantly shorter gestational length than spp. dominated non-secretors (mean of 241.54 days (sd=47.14) versus 266.21 (23.61); -value=0.0251). Similar gestational length differences were observed between non-secretors with high vaginal diversity and secretors with spp. dominance (mean of 262.52 days (SD=27.73); -=0.0439) or depletion (mean of 266.05 days (SD=20.81); -=0.0312). Our data highlight secretor status and blood-group antigen expression as being important mediators of vaginal microbiota-host interactions in the context of preterm birth risk.