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182: Elevated vaginal sialidase activity is a predictive marker of early preterm birth among bacterial vaginosis positive women

      Objective

      Bacterial vaginosis (BV) has been positively associated with preterm birth, however only few BV positive pregnant women will have an adverse pregnancy outcome. Thus, more effective markers of risk are necessary to properly select women which require treatment. We aimed to assess if an objective and non-invasive vaginal fluid biomarker, sialidase activity, is an early predictor for preterm birth (20 to <37 weeks′ gestation), and particularly for early preterm birth (<34 weeks′ gestation).

      Study Design

      Low and high cutoffs for sialidase activity were examined in a case-control study of 461 BV positive US women (from a study population of 1,806 women enrolled in Philadelphia) with samples collected at mean 12 weeks′ gestation. A total of 69 preterm deliveries (53 spontaneous), 31 miscarriages and 352 normal term deliveries (>37 weeks′ gestation, birth weight >2500 g) vaginal fluids were analyzed for sialidase activity.

      Results

      Any positive sialidase activity (>0.19 nmol of converted substrate) was not associated with adverse pregnancy outcomes. Conversely, progressively high sialidase activity cutoffs were significantly associated with increased risk of adverse outcomes. Specifically, sialidase activity >5, and >10 nmol of converted substrate demonstrated odds ratio (OR) 1.56 (CI 1.01-2.41), and OR 2.14 (CI 1.25-3.64), respectively, for a composite variable including all adverse birth outcomes. However, only the highest sialidase cutoff was significantly associated with early preterm births (20-<34 weeks′ gestation), with OR 3.57 (CI 1.61-7.92). None of the sialidase thresholds predicted late preterm birth at 34-<37 weeks′ gestation.

      Conclusion

      In this US population of mostly black, poor pregnant women, early gestation finding of elevated sialidase in vaginal fluid was strongly associated with early preterm birth.