An exploratory study of associations with spontaneous preterm birth in primigravid pregnant women with a normal cervical length.

BACKGROUND

Predictors of spontaneous preterm birth in primigravid women remain undetermined.

AIM

We evaluated whether biomarkers in vaginal secretions and/or differences in the dominant bacterium in the vaginal microbiome predicted the risk for spontaneous preterm birth in primigravid women with a cervical length >25mm.

STUDY DESIGN

In a prospective study, 146 second trimester pregnant women with their first conception and a cervix >25mm were enrolled. The vaginal microbiome composition was characterized by analysis of 16S ribosomal RNA gene sequences. The concentrations of d- and l-lactic acid, matrix metalloproteinase (MMP) 2, 8 and 9 and tissue inhibitor of metalloproteinase (TIMP) 1 and 2 in vaginal secretions were measured by ELISA. Cervical length was determined by vaginal ultrasonography. Pregnancy outcome data were subsequently collected. There was a spontaneous preterm birth (SPTB) in 13 women (8.9%) while in an additional 8 women (5.5%) preterm delivery was medically indicated. was the dominant vaginal bacterium in 61.5% of women with a SPTB but only in 31.2% of those who delivered at term ( = .0354). The vaginal concentration of TIMP-1 ( = .0419) and L-lactic acid ( = .0495) was higher in women with a SPTB as compared to those who delivered at term. dominance was associated with elevated levels of TIMP-1 ( = .0434) and TIMP-2 ( = .0161) and lower levels of D-lactic acid ( < .0001) compared to when was dominant.

CONCLUSION

In this exploratory study of primigravid women, elevations in vaginal TIMP-1 and L- lactic acid and dominance in the vaginal microbiome are associated with an increased occurrence of SPTB.