Preface

Spontaneous childbirth is a phenomenon that leads to the exit of the fetus, placenta, and membranes from the pelvic cavity of the pregnant woman through the vagina. Childbirth is achieved with the necessary condition of periodic, involuntary, painful contractions of the uterus. A necessary condition for understanding childbirth is the knowledge of three factors: the uterus, the pelvic canal, and the fetus. The duration of pregnancy is genetically predetermined while it is also influenced by the environment.

The fetus is born after the end of its normal maturation, however, the factors that cause labor to occur in a full-term pregnancy have not been fully elucidated. Placental corticotropin acts in the fetoplacental unit, which creates a suitable endocrine environment for the initiation of labor through the pituitary–adrenal axis and the placenta.

In the mother, changes in the function of the placenta due to the increased concentration of pro-inflammatory factors (cytokines and interleukins) create the appropriate hormonal environment, while the synthesis of prostaglandins and oxytocin facilitates the response of the myometrium and cervix.

During pregnancy, contractions of the myometrium take place with the action of estrogens and prostaglandins, but initially, they do not spread throughout the body of the uterus. Later in pregnancy, intercellular connections between the smooth muscle fibers in the myometrium are progressively established, and as the electrical activity is transmitted from cell to cell, the myometrium contracts in a coordinated and localized manner, and Braxton Hicks contractions occur.

At the onset of labor, oxytocin circulates in high concentrations in the mother and its receptors develop on the surface of the smooth muscle cells of the uterus. Prostaglandins enhance the action of oxytocin, while estrogens facilitate the production of prostaglandins from the placenta. Other factors such as interleukin and cytokines further facilitate the coordinated activity of the myometrium at the onset and duration of labor.

Some cases of labor not progressing may be due to a lack of synchronization between cervical ripening and myometrial contractions.

Although many of the factors involved in the initiation of labor affect both the myometrium and cervix in different ways, oxytocin is a hormone that acts almost exclusively on the myometrium and has little effect on the cervix.

The diagnosis of labor is of great importance, as the incorrect diagnosis can lead to iatrogenic interventions that may not be needed or even to complications. For the diagnosis of labor, there must be the start of regular uterine contractions and progressive changes in the cervix.

However, the diagnosis of regular uterine contractions (labor pains) is quite problematic, as is their differential diagnosis from Braxton Hicks contractions. That is why the diagnosis of labor is made by examining the cervix and the upcoming changes in it. Friedman's

graphic representation that laid the foundation for modern labor monitoring practice uses changes in the cervix to define the latent and active phases of the first stage of labor.

Contractions are manifested by the appearance of periodic contractions of the uterus and are intended to dilate the cervix, exit the fetus, and detach and exit the placenta and membranes. Each contraction shows a beginning, a peak, and a decline.

The intensity of the contraction is assessed clinically by placing the palm on the abdomen of the patient. The resting stage of the uterus also varies. The contraction frequency is the number of contractions within a certain time interval. The expected normal range is three to five contractions every 10 minutes. Along with the clinical assessment, continuous recording of the contractions is done with the help of an electronic head, which is placed on the abdomen of the pregnant woman (external tocography) or, more rarely, by placing an intra-amniotic catheter (internal tocography). The contractions and the birth must be treated in the way chosen by the obstetrician in consultation with the midwife. There are many decisions to be made, so the obstetrician must be aware of every possible option.

The contribution of attending physicians and midwives is important in dealing with problems that may arise during labor and birth. Access to information and practical and moral support are equally important. If both parents attend the relevant childbirth classes, they will be better informed and actively more supportive. This book is a manual with useful information for those practicing obstetrics in the "trenches" who need real advice on how to deal with real problems. It is a modern, practical reference guide to help solve problems of everyday obstetric practice.

> **Panagiotis Tsikouras** Professor, Department of Obstetrics and Gynecology, Democritus University of Thrace, Alexandroupolis, Greece

#### **Nikolaos Nikolettos**

Professor, Department of Obstetrics and Gynecology, Democritus University of Thrace, Alexandroupolis, Greece

#### **Werner Rath**

Professor, Gynecology and Obstetrics in the Faculty of Medicine, University of Kiel, Kiel, Germany

### **Friedrich Von Tempelhoff**

Professor, Gynecology and Obstetrics, St. Vinzenz Teaching Hospital, Hanau, Germany Section 1
