Aim:
To examine the role of the inflammation of the uterus and chorioamniotic membranes in the occurrence of the different types of uterine contractility dysfunction.

Material and methods:
The influence of inflammation of uterine layers, chorioamniotic membranes, umbilical cord on different types of labor activity abnormalities was examined in 382 patients with singleton pregnancies at 28-42 weeks' gestation who underwent Caesarean section for abnormal uterine contractions and other complications. Statistical analyses included the Mann-Whitney U, Chi-squared test, and logistic regression.

Results:
In control group, slight infiltration with polymorphonuclear leukocytes and macrophages of the myometrium and decidua of the lower uterine segment at term pregnancy was found in 59.7% and 73.6% of cases. The main clinical risk factors for placental and decidual membrane inflammation in patients with excessive uterine activity were prematurity, multiparity, group B streptococcus colonization, and duration of ruptured fetal membranes before the CS. In women with hypotonic uterine activity, decidual and myometrial inflammation was significantly associated with nulliparity and intrapartum factors, such as protracted active first stage of labor, advanced cervical dilation, and number of vaginal examinations.

Conclusions:
Mild inflammation of decidual membrane and myometrium of the lower uterine segment at term pregnancy is a physiological phenomenon that contributes to the initiation of labor. The inflammatory genesis of the uterine tachysystole against the background of intact myometrium was confirmed by the high value of aOR for deciduitis, hCAM and funisitis (2.6, 4.5, 2.9) in patients in the EUA group. Decreased uterine contractility was associated with severe deciduitis (aOR: 1.4) and myometritis (aOR: 3.9).