ABO blood group antigens and preterm birth risk

Abstract

<h3>Background</h3><p>Host-vaginal-microbial interactions have been shown to influence spontaneous preterm birth (sPTB) risk(1,2). In other body niches, histo-blood group antigens are associated with microbiota composition and disease risk(3,4).</p><h3>Objective</h3><p>To investigate whether ABO blood group influences sPTB risk, and if this is associated with changes in vaginal microbial composition and host immune response.</p><h3>Methods</h3><p>Prospective study of women defined as at-risk of sPTB (n=1935), where cervicovaginal fluid (CVF) was collected in pregnancy (20-24 weeks). Bacterial DNA was extracted, and the composition assessed using 16 S rRNA gene sequencing surveying the V1-V2 region (n=238). Cytokine immunoassays were performed on matched CVF supernatant (n=103). Results were analysed according to ABO blood group status and risk factor for sPTB.</p><h3>Results</h3><p>In women at risk of sPTB with previous cervical treatment blood group B was associated with a higher risk of sPTB<34weeks than A (RR 2.94(1.22-7.64), p=0.01), yet no correlation was seen with CVF cytokine concentration. In women with previous mid-trimester loss (MTL)/PTB those with blood group O were at increased risk of sPTB <34 weeks compared to those of blood group A (RR 1.42(0.94-2.17), p=0.04). IL-8 levels were higher in women of blood group O with a previous MTL/PTB than those of blood group A or B. IL-8 was also correlated with L. iners and bacterial vaginosis-associated taxa in women of blood group O with sPTB.</p><h3>Conclusions</h3><p>ABO blood groups influence vaginal microbial composition, local inflammation and risk of sPTB, and provide mechanistic insight on the different aetiologies of PTB.</p>