The Biomarkers for Preterm Birth Study-A prospective observational study comparing the impact of vaginal biomarkers on clinical practice when used in women with symptoms of preterm labor

Abstract

Introduction: This study aims to compare the use of qualitative fetal fibronectin, quantitative fetal fibronectin, and placental α-microglobulin-1 in women with symptoms of preterm labor, to evaluate which vaginal biomarker performs the best in clinical practice.

Material and methods: This prospective observational study included women who presented with symptoms of preterm labor at 24+0 to 34+0 weeks of gestation at a large tertiary maternity hospital in Auckland, New Zealand. Women were managed according to hospital guidelines using qualitative fetal fibronectin. Quantitative fetal fibronectin and placental α-microglobulin-1 tests were also taken, with clinicians blinded to the results. Management and delivery outcomes were collected from clinical records. The primary outcome was the rate of antenatal hospital admission. Analysis was performed according to predefined management protocols for each of the tests.

Results: A total of 128 women had all three biomarkers tests taken. Spontaneous preterm birth rates were 7/128 (5.5%) ≤34+0 weeks and 20/128 (15.6%) <37+0 weeks of gestation; 5/128 (3.9%) delivered within 7 days of testing. Positive results were recorded in 28 qualitative fetal fibronectin tests, 25 quantitative fetal fibronectin tests with 11 ≥200 ng/mL, and 16 placental α-microglobulin-1 tests. The use of quantitative fetal fibronectin or placental α-microglobulin-1 would have lowered antenatal admission rates: 27/128 (21.1%) for qualitative fetal fibronectin, 11/128 (8.6%) for quantitative fetal fibronectin (admission threshold ≥200 ng/mL), and 15/128 (11.7%) for placental α-microglobulin-1. No additional women with quantitative fetal fibronectin <200 ng/mL delivered within 7 days or missed corticosteroids compared with standard care (qualitative fetal fibronectin); however, an additional 3 cases had a false-negative placental α-microglobulin-1 and clinical care may have been compromised (no antenatal corticosteroids or admission).

Conclusions: The use of quantitative fetal fibronectin (admission threshold ≥200 ng/mL) has the potential to reduce the rate of antenatal admissions for women with symptoms of preterm labor without compromising use of antenatal interventions that improve outcomes for babies born preterm.