Association between miRNAs in serum at 10-14 gestational weeks and spontaneous preterm delivery.

ABSTRACT

INTRODUCTION: Preterm delivery (PTD) is the leading cause of death in children under 5 years of age. Cervical shortening detected by ultrasound can be used to predict PTD, but prediction is not perfect, and complementary diagnostic markers are needed. Recently, specific plasma microribonucleic acid (miRNAs) detected in early second trimester were shown to be associated with spontaneous PTD in high-risk women with a singleton pregnancy. The aim of this study was to explore to what extent these miRNAs are associated with spontaneous PTD and cervical length in a general population. MATERIAL AND METHODS: This study is a nested case-control study within the CERVIX study. The CERVIX study evaluated the ability of cervical length screening with transvaginal ultrasound to identify women at risk of PTD. In the present study, women who delivered spontaneously <34 weeks (n = 61) were compared with a control group of women who delivered at full term (39 + 0 to 40 + 6 gestational weeks, n = 205). Archived serum samples were analyzed with RT-qPCR for miRNA expression levels of let-7a-5p, miR-150-5p, miR-15b-5p, miR-185-5p, miR-191-5p, miR-19b-3p, miR-23a-3p, miR-374a-5p, and miR-93-5p. The mean relative expression was compared between the groups. Sub-analyses were performed for women delivering <32, <30, and <28 weeks vs the full-term group. RESULTS: The analyzed miRNAs were not significantly differentially expressed in women delivering <34 weeks compared to those delivering at full term. MiR-191-5p and miR-93-5p were significantly overexpressed in women who delivered <32 weeks, and further increase in fold change was observed with decreasing gestational age at delivery. The level of miR-15b-5p was significantly higher in women delivering at <30 weeks compared to those delivering at full term. CONCLUSIONS: Our study shows that overexpression of miR-93-5p, miR-15b-5p, and miR-191-5p in serum at early gestation is associated with spontaneous PTD in a general population. Further research is needed to evaluate the potential of these miRNAs as future biomarkers for spontaneous PTD, as well as their pathophysiological role in spontaneous PTD.