The principle of morpho-functional symmetry-asymmetry in the formation of contractile activity of the uterus during physiological and complicated pregnancy

The functional pairing of the uterus determines the formation of localized and generalized forms of uterine activity, the study of which makes it possible to identify contractile predictors of preterm birth. Normally, uterine contractions first occur in the II–III trimesters of pregnancy and their aim is to ensure an optimal level of blood flow and transplacental exchange in the uteroplacental complex within the framework of the uteroplacental “pump”. It is of value importance to search those forms of uterine contractions that accompany preterm labor. Since uterine contractions are initiated predominantly in the subplacental area of the myometrium, the modulating role in this process belongs to the area where the placenta is located. Aim: The identification of the characteristics of contractions in the right and left parts of the uterus in physiological and complicated pregnancy, depending on the area of predominant location of the placenta. Materials and methods: 149 women with uncomplicated pregnancy and 126 with premature birth were examined. Features of contractile activity of the uterus were revealed using mechanohysterography for 40 minutes from symmetrical sections of the left and right sections of the anterior abdominal wall at the level of the umbilical ring. Results: It has been established that the physiological course of gestation is characterized by asymmetrical (right- and left-sided) forms of uterine contractions, regardless of the location of the placenta. The right parts of the uterus are normally more functionally active compared to the left. Conclusion: For uncomplicated pregnancy, unilateral contractions are most common, which help to maintain constant intra-amniotic pressure and preserve the lower uterine segment and cervix, because according to the physiological mechanism, they are isotonic. Women with preterm birth have symmetrical bilateral contractile uterine activity, which is isometric, leading to increased intra-amnial pressure, cervical shortening and ripening and preterm birth.