Midpregnancy Vaginal Fluid Defensins, Bacterial Vaginosis, and Risk of Preterm Delivery

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Abstract
OBJECTIVE: To assess relations among midpregnancy vaginal defensin levels, a component of the host innate immune response, bacterial vaginosis, and risk of preterm delivery. These relations are compared across race groups because previous studies have repeatedly shown that the prevalence of bacterial vaginosis and the risk of preterm delivery are greater in African-American women compared with that in white women. METHODS: Data are from a prospective study that enrolled pregnant women from 52 clinics in five Michigan communities. In the study subcohort, defensins (human neutrophil peptides 1, 2 and 3) and bacterial vaginosis (Nugent criteria) were measured in vaginal fluid collected at enrollment (15th through 27th week of pregnancy) from 1,031 non-Hispanic white and African-American women (787 term, 244 preterm). Preterm deliveries were categorized by clinical circumstances, ie, spontaneous and medically indicated. RESULTS: Among African Americans, vaginal human neutrophil peptides 1–3 levels greater than or equal to the median were associated with bacterial vaginosis and specifically with spontaneous preterm delivery only (adjusted odds ratio 2.3, 95% confidence interval 1.2–4.3). Once African-American women were stratified by human neutrophil peptide 1–3 levels, bacterial vaginosis added nothing to the prediction of spontaneous preterm delivery risk. None of the above associations were observed in non-Hispanic whites. CONCLUSION: The relations among human neutrophil peptide 1–3 levels, bacterial vaginosis, and preterm delivery vary by race group. In African Americans, midpregnancy human neutrophil peptide 1–3 levels were more informative to preterm delivery risk than was bacterial vaginosis, suggesting an important role for host response. In addition, elevated human neutrophil peptide 1–3 levels may be a marker for particular high-risk vaginal milieus that are not distinguished by the current bacterial vaginosis Nugent scoring system. LEVEL OF EVIDENCE: II