Matrix metalloproteinase-9 as a potential marker of preterm birth

Relevance: Preterm birth (PB) is a significant issue worldwide as it is the leading cause of perinatal morbidity and mortality. International statistics indicate that 5–18% of pregnancies result in PB.

Objective: This study aimed to investigate changes in blood plasma and cervicovaginal secretion concentrations of matrix metalloproteinase-9 (MMP-9) in pregnant women with threatened PB, as well as the dynamics of MMP-9 concentrations in response to tocolytic therapy with hexoprenaline.

Materials and methods: We examined 45 pregnant women with threatened PB. The control group consisted of 40 women with healthy pregnancies. The inclusion criterion was a singleton spontaneous pregnancy at 24–31 weeks and 6 days of gestation, with signs of threatened PB. Exclusion criteria were multiple pregnancies, acute phase or exacerbation of chronic diseases, history of cervical pathology, cancer and autoimmune diseases, preeclampsia and its complications, chromosomal abnormalities and congenital fetal malformations, pregnancies resulting from assisted reproductive technologies, and premature rupture of membranes.

Results: Blood plasma MMP-9 concentrations in women with threatened PB and those with normal pregnancies were virtually identical, measuring 116 and 120 ng/ml, respectively. In patients with threatened PB, the mean cervical secretion concentration of MMP-9 was 6.48 pc/g. After tocolytic therapy with hexoprenaline, the concentration decreased to 1.5 pc/g, which was comparable to the cervical secretion concentration of MMP-9 in pregnant women in the control group (1.58 pc/g).

Conclusion: Our study demonstrated that blood plasma MMP-9 cannot serve as a marker of PB because we did not observe any changes in its concentration during threatened PB. However, MMP-9 in cervicovaginal fluid may be considered a marker of PB, as its concentration increases in threatened PB and decreases in response to tocolytic therapy with hexoprenaline, reaching levels typical of a normal pregnancy.