Objective To evaluate the microbial load and the inflammatory response in the distal and proximal parts of the cervical mucus plug. Design Experimental research. Population Twenty women with a normal, singleton pregnancy. Sample Vaginal swabs and specimens from the distal and proximal parts of the cervical mucus plug. Methods. Immunohistochemistry, enzyme-linked immunosorbent assay, quantitative polymerase chain reaction and histology. Results The total bacterial load (16S rDNA) was significantly lower in the cervical mucus plug compared with the vagina (p = 0.001). Among women harboring Ureaplasma parvum, the median genome equivalents/g were 1574 (interquartile range 2526) in the proximal part, 657 (interquartile range 1620) in the distal part and 60 240 (interquartile range 96 386) in the vagina. Histological examinations and quantitative polymerase chain reaction revealed considerable amounts of lactobacilli and inflammatory cells in both parts of the cervical mucus plug. The matrix metalloproteinase-8 concentration was decreased in the proximal part of the plug compared with the distal part (p = 0.08). Conclusion The cervical mucus plug inhibits, but does not block, the passage of Ureaplasma parvum during its ascending route from the vagina through the cervical canal.

Introduction The viscoelastic properties of the cervical mucus plug are considered essential for the occlusion of the cervical canal and thereby for protection against ascending infections during pregnancy. Factors controlling this property are virtually unknown. This study explores a possible role of trefoil factor peptides 1, 2 and 3 (TFF1–3); peptides believed to influence mucus viscosity. Material and methods The study is based on spontaneously shed cervical mucus plugs from 14 women in active labor. The viscoelastic properties; the elastic modulus (G') and the viscous modulus (G”) were determined by an oscillatory rheometer. The concentrations of TFF1–3 were measured by an in‐house enzyme‐linked immunosorbent assay. Associations were analyzed by random‐effects generalized least‐squares regression analyses. Results Median (range) concentrations of TFF1, TFF2 and TFF3 were 3.1 (1.2–8.6), 1.1 (<0.006–3.7) and 1000 (170–5300) nmol/g cervical mucus plug, respectively. The TFF3 concentration was associated with G' (regression coefficient 11.7 Pa/Log nm; 95% CI 3.0–20.4, p = 0.009) and G” (regression coefficient 3.2 Pa/Log nm; 95% CI 1.5–5.0, p < 0.001). Conclusion We suggest that TFF3 plays a role in the viscoelastic properties of the cervical mucus plug.

The CMPs are solid-like viscoelastic structures. These rheological characteristics are probably essential for the CMP's ability to form and sustain a plug in the cervical canal during pregnancy, thereby reducing the risk of ascending infections. The technique described here might be used for evaluation of an association between CMP viscoelasticity and preterm delivery.