Zeitschrift fur Geburtshilfe und Perinatologie最新文献

The causes of prolonged pregnancy are still largely unknown and their investigation requires a detailed observation of potential birth-initiating stimuli on the endocrine and biomolecular level. A large number of clinical and biochemical studies point to the central importance of prostaglandins for the beginning of human birth. The main places of origin of the intensified prostaglandin formation and release are the amnion and the decidua which has "macrophage-like" properties and functions. The superordinate regulation and trigger mechanisms for intensified uterine prostaglandin production has not been sufficiently investigated either. Possible factors currently being debated include local changes in estrogen and progesterone biosynthesis in fetal membranes and decidua, subclinical inflammatory reactions with the activation of macrophages and the consecutive release of cytokines, and a loss of maternal immune tolerance with a time-determined rejection reaction. In addition, the substances inhibiting and stimulating prostaglandin synthesis have been detected in the amniotic fluid, fetal membranes and decidua. The fetus itself also plays an important part in the initiation of labor. Prolongation may be due to anatomic functional disturbances of the one hand which prevent the activation of the fetal hypothalamic-hypophyseal-adrenal axis and the release of the birth-initiating stimuli originating in the fetus; on the other hand, an elevated immune tolerance with a delayed rejection reaction or the lack of "bacterial stimulus" may inhibit the activation of the macrophages and hence the formation of cytokines. The consequences would be the development and release of a quantity of prostaglandins from the fetal membranes and decidua insufficient to overcome the pregnancy-maintaining safety systems.(ABSTRACT TRUNCATED AT 250 WORDS)

The cervix uteri is of greatest importance for the environment of the fetus. The sonographic imaging of the cervix uteri can be done by transabdominal, perineal and transvaginal route. Each of these methods are associated with specific advantages and disadvantages. During the time of gestation the cervix uteri can be measured sonographically concerning the length, the thickness, the width of the cervical canal and in addition the diameter of the internal and the external os. At the beginning of labour the cervix shows a transformation: a shortening with an increase of thickness. The phase of contraction is followed by a phase of reformation. Individual formations of the cervix regarding the a premature opening of the internal os or the external os could be demonstrable without clinical symptoms. By W. Eppel a score-like formula "Incompetence-Factor" was described for a quantification of these measurements.

A survey is given about the general theories of beginning of labour. In this topic the influence of excitation of the uterus muscle is explained together with the importance of hormonal induction.

A four-channel topographic technique was developed in order to improve information about spatial uterine motility. 54 women were monitored during delivery. Four pressure transducers were attached in a square around the umbilicus. Most frequently the origin of labour could be determined in the upper right segment of the uterus. The rate of operative deliveries was decreased in case of predominant upper right origin of labour. The majority of contractions with clear propagation patterns originated at the upper right site, continued to the left and then to the lower right part of the uterus. The highest relative intensity was also measured at the upper right site. Predominant upper right origin of labour may be important for undisturbed delivery. The probability of a preterm delivery is increased in case of an upper right origin of labour.

It is especially in the long-term application where the pharmacodynamics of the betamimetics determine their effectiveness. According to the time and dosis, there is a decrease in the density and function of the beta 2-adrenoceptors (desensitization). Clinically, this means a loss of effectiveness. This study investigated whether in the course of a normal pregnancy (n = 22) there is a change in the effectiveness of the betamimetics, as expressed by a change in the number of beta 2-adrenoceptors or their function. The results show a 50% decrease in the number of beta 2-adrenoceptors to the 36th gestational week and an increase to initial values after delivery. A similar pattern is found for the function of the beta 2-adrenoceptors (cyclic AMP). The implications for the uterus might be that, with advancing pregnancy, it becomes less prone to relaxation and that the betaadrenergic system, as a mechanism supporting prepare the way for delivery at term, becomes less significant. For tocolysis with betamimetics, the decrease of the beta 2-adrenoceptor density means that, with increasing gestational age, the responsiveness of the uterus to betamimetics decreases.

The central function of the cervix to maintain pregnancy is biochemically characterized by an increased synthesis of collagen, proteins, glycosaminoglycans (GAG) and fibronectin within the extracellular matrix, thus leading to an increase of cervical volume without significant changes of cervical consistency. During the time of cervical ripening we found a marked reduction of collagen concentration, a 2.5-fold increase in GAG content, a significant fall in dermatan sulfate concentrations from 41% to 15% of total GAG content, a 12-fold increase in hyaluronate concentrations, and a marked reduction in fibronectin, demonstrated by immunhistochemical methods. Thus, the loss of collagen and sulfated GAGs may facilitate distensibility in the ripened cervix, while the significant gain in hyaluronate associated with hydratation may explain the soft and swollen consistency. In this connection increased hyaluronate concentrations and degradation of fibronectin may play a trigger role for subsequent cervical dilatation. The dramatic changes of the cervix during parturition occurring within a few hours require the rapid activation and action of catabolic enzyme systems. Our studies showed a significant increase of sialidase-, collagenase- and elastase activities during cervical dilatation. These proteinases originate from polymorphonuclear leucocytes (pml), which accumulate in cervical capillaries at the onset of labor; this is followed by a massive leucocyte infiltration of the cervical stroma at the beginning of cervical dilatation and a degranulation of the pml at further dilatation, thus releasing collagenase and other proteinases. This process is limited by the immediate post partum insudation of the cervix by plasma containing highly potent proteinase inhibitors. The clinical aim of our basic biochemical studies is to develop new concepts in the causal treatment of cervical pathology during pregnancy.

Prostaglandins and lipoxygenase metabolites of arachidonic acid (Eicosanoids) are crucial paracrine regulators of labor. There are many informations about in vitro production and the physiological or pathophysiological role and clinical importance of these substances. However, the all decisive mechanism of the involvement of eicosanoids in birth process is still unknown. In this review we describe the present knowledge about endocrine, paracrine and autocrine regulations of uterine contractions.

A great number of studies on women as well as experiments on animals support the association of silent intrauterine infection with the initiation of preterm labour. However, the success of antibiotic therapy in reducing bacteria-induced labour in animals could only be confirmed in few reports concerning women in preterm labour. Disregarding direct effects of bacterial products such as Phospholipase-A2 and endotoxins evidence suggests that immunological effects (release of Cytokines) may enhance the synthesis of prostaglandins in the uterus, placenta and fetal membranes. New therapeutical approaches are in discussion, but only time will tell whether a reduced rate of women with failed tocolysis will be the result.