The head of a mature fetus and its size. The concept of fetal maturity and term

It should be noted that full-term and fetal maturity are ambiguous concepts.

Term indicates the length of time the fetus remains in the mother's body.

Maturity characterizes the degree of development of the fetus.
Maturity is usually understood as a set of signs (level of physical development, development of the skin of soft tissues, musculoskeletal system), i.e., the degree of fetal development at which independent life of the child in the external environment is possible.
Among the signs of maturity of newborns, leading importance is given to:

Sufficient development of the subcutaneous fat layer;

The length of hair on the head is at least 2 cm;

The cartilage of the ears and nose is dense;

The nail plates on the fingers extend beyond the ends of the fingers, on the feet they reach the ends of the fingers;

Condition of the external genitalia and other signs.

Accelerated growth and physical development of the fetus can lead to the recognition of a newborn child as viable in cases where, by intrauterine age (less than 8 lunar months), viability in the forensic sense has not yet been achieved, which significantly changes the legal assessment of the fact of infanticide and responsibility for it.
The above should be taken into account by the investigator when assessing the expert’s conclusions.

Whether a baby is full-term or preterm is determined by whether the baby was born at term or prematurely.

The normal duration of pregnancy is 280 days, or 10 lunar months (a lunar month is 28 days). Deviations from this period are possible; in such cases, the baby will be considered premature or post-term.

The birth of a baby to term is characterized by a combination of a number of signs. Its body length is 50 cm, head circumference is 32 cm, the distance between the shoulders is 12 cm, between the trochanters of the thighs is 9.5 cm, weight is 3 kg.

The skin of a full-term baby is pink, elastic, and covered with delicate down in the shoulder area. The fingernails extend beyond the ends of the fingers, and the nails on the toes reach the ends. The cartilage of the nose and ears is dense and elastic. The mammary glands in boys and girls are slightly swollen. In boys, the testicles are located in the scrotum; in girls, the labia majora cover the labia minora. A transverse section of the distal epiphysis of the femur in the central part of the section clearly shows the so-called ossification nucleus in the form of a dark red focus with a maximum diameter of 0.5 cm, located against the background of white cartilaginous tissue.

A premature baby's body length, other dimensions and weight will be smaller the more premature he is. The skin is pale, flabby, wrinkled, and covered with fluff everywhere. The face has an old-looking appearance, the cartilages of the nose and ears lack elasticity. Fingernails and toenails do not reach the ends of the fingers. In boys, the scrotum is empty due to the location of the testicles in the abdominal cavity. In girls, the labia majora do not cover the labia minora.

A full-term baby is usually mature.

The weight of the fetus, the shape and size of the head, as well as the degree of maturity of the fetus are of great importance during childbirth. In most cases, the head is the presenting part, but it is very important that it also corresponds to the size of the pelvis.

Signs of fetal maturity:

A conclusion about fetal maturity is made by a pediatrician or obstetrician-gynecologist. In their absence, this should be done by a midwife. The length of a full-term fetus is more than 47 cm (with normal development no more than 53 cm). The weight of the fetus should be more than 2500 g. The optimal weight is 3000-3600 g. With a weight of 4000 g or more, the child is considered large, with a weight of 5000 g or more - gigantic. The degree of maturity can be judged by bone density (according to fetal ultrasound, vaginal examination and examination of the newborn).

The skin of a mature newborn is pale pink in color, with well-defined subcutaneous fatty tissue, many folds, good turgor and elasticity, remains of a cheese-like lubricant, without the slightest signs of maceration.
The length of the hair on the head is more than 2 cm, the vellus hairs are short, the nails extend beyond the fingertips. Ear and nasal cartilage are elastic. The chest is convex, in a healthy child the movements are active, the cry is loud, the tone is active, reflexes are well expressed, including searching and sucking. The child opens his eyes. The umbilical ring is located in the middle of the distance between the pubis and the xiphoid process; in boys, the testicles are lowered into the scrotum; in girls, the labia minora are covered by the labia majora.

Head of a mature fetus:

The fetal skull consists of two frontal, two parietal, two temporal and one occipital bones, as well as the sphenoid and ethmoid bones. The bones of the skull are separated by sutures, of which the most necessary is knowledge of the sagittal, or sagittal, suture, which passes between the parietal bones and by which the position of the head is determined during occipital insertion. In addition, there are sutures: frontal, coronal, lambdoid. In the area where the sutures join, there are fontanelles, of which the large and small ones are of greatest importance.

The large fontanel is located at the junction of the streloid, frontal and coronal sutures and has a diamond shape. The small fontanel has a triangular shape and is located at the intersection of the sagittal and lambdoid sutures. The small fontanelle is the conducting point in the case of childbirth with anterior occipital presentation. The fetal head has a shape adapted to the size of the pelvis.

Thanks to the sutures and fontanelles, which are fibrous plates, the bones of the head are mobile. If necessary, the bones can even overlap one another, reducing the volume of the head (configure). On the head, it is customary to distinguish the sizes by which the head erupts during various biomechanisms of childbirth: small axial size, medium oblique size, large oblique size, pit size, vertical or vertical size, two transverse sizes.

In addition to the size of the head, the size of the shoulders is taken into account, which is on average 12 cm with a circumference of 34-35 cm, as well as the size of the buttocks, which is 9 cm with a circumference of 28 cm.

Determination of estimated fetal weight:

In order to assess fetal development and compliance with the birth canal, it is necessary to determine its estimated weight. In modern conditions, this can be done using ultrasound. The biparietal size of the head and the size of the limbs are determined, and from these data the computer calculates the probable weight of the fetus. Without ultrasound and a computer, you can use other methods and formulas:

Using Rudakov's method, the length and width of the semicircle of the palpated fetus are measured, and the weight of the fetus is determined using a special table.
According to the Jordania formula, the length of the abdominal circumference is multiplied by the height of the uterine fundus (for full-term pregnancy).
According to Johnson's formula. M = (VDM - 11) multiplied by 155, where M is the mass of the fetus; VDM - height of the uterine fundus; 11 and 155 special indexes.
According to the Lankowitz formula. It is necessary to add up the height of the uterine fundus, abdominal circumference, body weight and height of the woman in centimeters, and multiply the resulting amount by 10. When calculating, take the first 4 digits.

All methods for determining the estimated weight of the fetus, even the use of ultrasound, produce errors. And the use of external obstetric measurements sometimes gives very large errors, especially in very thin and very fat women. Therefore, it is better to use several methods and take into account your body type.

Biomechanism of childbirth:

The set of flexion, translation, rotation and extension movements performed by the fetus as it passes through the pelvis and soft parts of the birth canal is called the biomechanism of childbirth. A. Ya. Krassovsky and I. I. Yakovlev made a great contribution to the study of the mechanism of childbirth.

When considering the biomechanism of childbirth, the following concepts are used:
The leading (wire) point is the lowest point on the presenting part of the fetus, which enters the small pelvis, passes along the wire axis of the pelvis and is the first to emerge from the genital slit.
The point of fixation is the point by which the presenting or passing part of the fetus abuts the lower edge of the symphysis, the sacrum or the apex of the coccyx in order to flex or extend.
The moment of the biomechanism of childbirth is the most pronounced or main movement that the presenting part performs at a certain moment, passing through the birth canal.
It is necessary to distinguish between the concepts of presentation and insertion of the fetal head. Presentation is when the fetal head is not fixed and stands above the entrance to the pelvis. Insertion - the head is fixed to the plane of the entrance to the pelvis by a small or large segment, placed in one of its subsequent planes: in the wide, narrow part or at the exit from the pelvis.

So, the biomechanism of childbirth is a set of movements that the fetus makes when passing through the mother’s birth canal.

The features of the biomechanism of childbirth are influenced by presentation, insertion, type, shape and size of the pelvis and head of the fetus. First, the fetal head, and then the torso with limbs, move along the birth canal, the axis of which passes through the center of the classical planes of the pelvis. The advancement of the fetus is facilitated by contractions of the uterus and the parietal muscles of the pelvis.

Biomechanism of labor with anterior view of occipital insertion of the fetal head:

The first moment is the insertion and flexion of the fetal head. Under the influence of expelling forces, the head is inserted with its arrow-shaped suture into the transverse or one of the oblique dimensions of the plane of entry into the small pelvis. The back of the head and the small fontanelle are facing anteriorly. In the first position, the head is inserted with an arrow-shaped suture into the right oblique dimension, and in the second position - into the left oblique dimension of the plane of the entrance to the small pelvis.

During the expulsion period, the pressure of the uterus and abdominal press is transmitted from above to the fetal spine and through it to the head. The spine connects to the head not in the center, but closer to the back of the head (eccentrically). A double-armed lever is formed, the back of the head is placed on the short end, and the forehead on the long end. The pressure force of the expelling forces is transmitted through the spine primarily to the area of the back of the head - the short arm of the lever. The back of the head drops, the chin approaches the chest. The small fontanel is located below the large one and becomes the leading point. As a result of flexion, the head enters the pelvis with its smallest size - small oblique (9.5 cm). With this reduced circumference (32 cm), the head passes through all planes of the pelvis and the genital opening.

I. I. Yakovlev proposed dividing the first moment into two (separately considering insertion of the head and flexion of the head). He also noted that even during normal childbirth, the sagittal suture may deviate from the pelvic axis anteriorly or posteriorly, i.e., asynclitpic insertion (see: “Basic obstetric concepts”). True, during normal childbirth this physiological asynclitism with a deviation in each direction of approximately 1 cm.

As another point, I. I. Yakovlev identified sacral rotation, i.e., pendulum-like advancement of the fetal head with alternating deviation of the sagittal suture: either towards the promontory (anterior asynclitism), or towards the pubis (posterior asynclitism). One of the parietal bones drops forward, while the other lingers and then slips. The alignment of the head relative to the pelvic axis is determined by the configuration of the bones. Due to the pendulum-like movement, the head descends into the pelvic cavity.

Second moment - internal rotation of the fetal head. The internal rotation begins when it passes from the wide part of the small pelvis to the narrow part and ends at the pelvic floor. The head moves forward (lowers) and simultaneously rotates around the longitudinal axis. In this case, the back of the head turns anteriorly, and the forehead - posteriorly. When the head descends into the pelvic cavity, the sagittal suture changes to an oblique size: in the first position - to the right oblique, and in the second - to the left. At the outlet of the pelvis, a sagittal suture is installed in its direct size. During the rotation, the back of the head moves in an arc of 90° or 45°.

With the internal rotation of the head, the sagittal suture passes from transverse to oblique and, on the pelvic floor, to the direct dimension of the plane of exit from the small pelvis. Internal rotation of the head is associated with various reasons. It is possible that this is facilitated by the adaptation of the advancing head to the dimensions of the pelvis: the head, with its smallest circumference, passes through the largest dimensions of the pelvis. At the entrance the largest dimension is transverse, at the cavity it is oblique, at the exit it is straight. Accordingly, the head rotates from a transverse dimension to an oblique dimension and then to a straight dimension. I. I. Yakovlev associated the rotation of the head with contraction of the pelvic floor muscles.

III moment - extension of the head. Contraction of the uterus and abdominal press expels the fetus towards the apex of the sacrum and coccyx. The pelvic floor muscles resist the movement of the head in this direction and contribute to its deviation anteriorly, towards the genital opening. Extension occurs after the area of the suboccipital fossa comes under the pubic arch. The head is extended around this fixation point. During extension, the forehead, face and chin erupt - the entire head is born. Extension of the head occurs during cutting and cutting through the vulva with a circle (32 cm) passing through the small oblique dimension.

IV moment - internal rotation of the shoulders and external rotation of the fetal head. During extension of the head, the shoulders with their largest size (biacromial) are inserted into the transverse dimension or into one of the oblique dimensions of the pelvis - opposite to where the sagittal suture of the head was inserted.

When moving from the wide part of the small pelvis to the narrow part, the shoulders, moving in a helical manner, begin an internal rotation and, thanks to this, move into an oblique, and on the pelvic floor - into a straight size of the outlet from the small pelvis. The internal rotation of the shoulders is transmitted through the neck to the newborn head. In this case, the fetus’s face turns toward the mother’s right (in the first position) or left (in the second position) thigh. The back of the baby's head turns toward the mother's hip, which corresponds to the position of the fetus (in the first position, to the left, in the second, to the right).

The posterior shoulder is located in the sacral recess, and the anterior shoulder erupts to the upper third (to the point of attachment of the deltoid muscle to the humerus) and rests on the lower edge of the symphysis. A second fixation point is formed, around which lateral flexion of the fetal torso occurs in the cervicothoracic region in accordance with the direction of deepening of the birth canal. In this case, the posterior shoulder is born over the perineum, and then the anterior shoulder is completely released. After the birth of the shoulder girdle, the birth of the baby’s body, which is less voluminous compared to the head and shoulder girdle, occurs quickly and without obstacles.

Biomechanism of labor in the posterior view of the occipital insertion of the fetal head:

The formation of a posterior view of the occipital presentation may depend on the condition of the fetus (the largest size of the head, poor mobility of the cervical vertebrae, etc.), on the birth canal of the pregnant woman (anomalies of the pelvis or pelvic floor muscles, etc.). The posterior view often becomes anterior during the process of expulsion. The head rotates 135°. However, in some cases (1% with internal rotation), the head rotates from the back of the head to the sacrum, and birth occurs in the posterior view.

I moment - flexion of the head. The small fontanelle becomes a wire point. In the pelvic cavity, during rotation, the midpoint between the small and large fontanels becomes the wire point. The head, with its swept suture (small fontanel at the back), is inserted into the transverse or one of the oblique dimensions of the plane of entry into the small pelvis. The head bends to a medium oblique size.

Second moment - internal rotation of the head. It begins at the transition of the head from the wide to the narrow part of the small pelvis and ends at the pelvic floor. In this case, there may be several options for turning into a posterior or anterior view of the occipital presentation. If the original rear view remains in this view, then the head rotations can occur as follows:

1. When inserted into one of the oblique dimensions of the plane of entry into the pelvis, the head describes an arc of 45° or less; the small fontanel turns posteriorly, and the large one - anteriorly.
2. When the head is inserted into the transverse dimension of the plane of entry into the small pelvis, it is rotated 90° so that the sagittal suture passes from transverse to oblique (according to the position), and then to the direct dimension of the plane of exit from the small pelvis, while the small fontanel rotates to the sacrum, and the large one to the symphysis.
3. If the rear view turns into the front view, then the head rotates as follows:
in the posterior view of the second position, the sagittal suture rotates clockwise, moving from the right oblique to the transverse, then to the left oblique and, finally, to the direct dimension of the plane of exit from the pelvis;
in the posterior view of the first position, the sagittal suture of the head turns counterclockwise, moving from the left oblique first to the transverse, then to the right oblique and, finally, to the direct size of the outlet from the pelvis; in this case, the small fontanel describes a large arc - about 135° and stops near the pubic symphysis with a small fontanel.

III moment - additional flexion of the fetal head. After completing the internal rotation, the head fits under the symphysis pubis with the border of the scalp of the forehead. The first fixation point is formed. The head is bent as much as possible so that the occipital part drops as low as possible. The parietal and occipital tubercles erupt.

IV moment - extension of the fetal head. After the birth of the parietal tuberosity and occipital tubercle, the head rests on the sacrococcygeal joint in the region of the suboccipital fossa - the second point of fixation. Around this point of fixation, extension occurs and the rest of the forehead and face are born. The head erupts through the genital slit with an average oblique size (10 cm, circumference 33 cm).

V moment - internal rotation of the shoulders and external rotation of the fetal head. It occurs in the same way as with the anterior view of the occipital presentation. With the posterior view of the occipital presentation, the movement of the head along the birth canal occurs with difficulty, and the expulsion period is longer than with the anterior view. Additional flexion of the head occurs with strong and prolonged attempts, and the woman in labor expends a lot of effort. The pelvic floor is subject to greater stretching, and perineal ruptures occur more often. Due to the length of the expulsion period and the difficult movement of the head through the birth canal, disturbances in fetal gas exchange often occur.

The influence of the mechanism of labor on the shape of the head:

The head, passing through the birth canal, adapts to the shape and size of the mother's pelvis. Under pressure from the walls of the birth canal, the bones of the skull move one onto another in the area of sutures and fontanelles, for example, one parietal bone overlaps the other, the occipital and frontal bones can overlap the parietal bones. As a result of these displacements, the shape of the head changes, adapting it to the shape and size of the birth canal.

The change in the shape of the head as it passes through the birth canal is called configuration. The wider the sutures and the softer the bones, the greater the ability of the head to be shaped. The configuration is especially significant when the pelvis narrows. The shape of the head changes depending on the mechanism of labor. In cases of occipital presentation, the head extends towards the back of the head, taking on a dolichocephalic shape. With an anterior cephalic presentation, the head is elongated in the direction of the crown, with a frontal presentation - in the direction of the forehead, etc. Most often, the configuration of the head is blurred, does not affect health and disappears soon after birth.

A birth tumor appears on the presenting part in the area of the wire point. It is a swelling, swelling of the tissues in the lowest anterior portion of the presenting part. Tissue swelling occurs due to difficulty in the outflow of venous blood from that area of the presenting part, which is located below the contact belt. It is formed after the outpouring of water only in living fruits. It gets worse with cervical rigidity. In occipital presentation, the birth tumor is located in the area of the small fontanelle and spreads to the right or left parietal bone, depending on the position.

In the first position, most of the birth tumor is on the right parietal bone, in the second position - on the left. In cases of facial presentation, the birth tumor forms on the face, and in cases of breech presentation, on the buttock. During normal childbirth, the birth tumor does not reach large sizes and disappears a few days after birth. If the expulsion period is prolonged (for example, with a narrow pelvis), the tumor reaches a large size, and the skin in the area of the tumor becomes purplish-red. With very fast labor and a small head, the birth tumor is insignificant or does not form at all.

If there is difficulty in the passage of the head through the birth canal and surgical delivery, a blood tumor or cephalhematoma may occur on the head, which is formed as a result of hemorrhage under the periosteum of one, less often both parietal bones; it is a soft, irregularly shaped swelling located within one bone, and does not go beyond the line of border sutures and fontanelles.

Ancestral expelling forces:

Labor expelling forces include contractions and pushing.
Contractions are periodically repeated contractions of the uterine muscles.
Pushing is a rhythmic contraction of the abdominal muscles and parietal muscles of the pelvis and pelvic floor that join contractions.

Thanks to contractions, the cervix opens, which is necessary for the passage of the fetus and placenta from the uterine cavity; contractions contribute to the expulsion of the fetus, pushing it out of the uterus.

Each contraction develops in a certain sequence, according to the rule of a triple downward gradient. First, a group of cells begins to contract in one of the upper parts of the uterine body (pacemakers), contractions spread to the fundus of the uterus, then to the entire body of the uterus and, finally, to the area of the lower segment and cervix. Contractions of the uterus gradually increase, reach their highest degree, then the muscles relax, turning into a pause.

Characteristics of the contraction: duration, frequency, strength, rate of increase and decrease, pain. When determining the frequency, duration and strength of cotton wool, one cannot take into account only the information received by the mother in labor. The woman calculates the duration of the cotton wool, focusing on the pain sensations. This subjective information may not be accurate.

A woman can react very painfully to subthreshold precursor contractions; sometimes she does not feel the onset of a contraction or may feel pain after the contraction stops and relaxes (trace reaction). The midwife, examining contractile activity, places the palms of her hands with fingers apart on the front wall of the uterus (one palm closer to the bottom, the second to the lower segment), i.e., controlling contractions in all parts of the uterus. Such contractions and relaxations of the uterus must be monitored for at least three contractions, note the strength, regularity, and direction of spread of myometrial contractions (triple downward gradient).

More objective data is provided by tonometry (registration of uterine contractions using a hysterograph or tocograph). The strength of contraction during ultrasound tonometry is estimated in mm Hg. Art. When palpating, the strength of the contraction is determined by qualitative criteria (weak, moderate, strong), this skill is passed on from teacher to student during practical training in the clinic. The pain of contractions is characterized by the woman herself. Soreness is very subjectively divided into weak, moderate and strong.

At the beginning of labor, the duration of contractions is only 20 seconds, by the end - almost 1 minute. The pauses between contractions at the beginning of labor last 10 minutes, then shorten; by the end of the period of expulsion of the fetus, contractions occur every 3 minutes. As labor progresses, contractions become stronger and more painful. Contractions may be frequent, prolonged and painful, but weak. In this case, they already talk about anomalies of labor.

There are three types of contractions of the uterine muscles: contraction, retraction and distraction.
Contractions are contractions of the muscles of the uterus, followed by their relaxation; they are characteristic of the body of the uterus, thanks to which the fetus is pushed out of the fetal sac. Contractile contractions are the most active type of contraction.

Retractions are contractions of the muscles of the uterus, which are combined with their displacement. Some fibers are pushed into others, and after displacement they do not return to their place. Such contractions are characteristic of the lower part of the uterus, with them the lower muscle fibers are shortened and this helps to improve distraction and dilatation of the cervix. The neck and lower segment stretch, become thinner and move upward. At the same time, at the border with the upper parts of the uterus, above which no retractions are observed, but only contraction contractions take place, a border, or contraction, ring is formed. It is formed by muscle fibers displaced upward. The contraction ring is located above the upper edge of the symphysis by as many transverse fingers or centimeters as the cervix is open (this can be used for diagnostic purposes).

Distraction is the relaxation of the circular (circular) muscles of the cervix, which promotes dilatation of the cervix.

Consequently, due to contractions, the fetus is expelled from the fetal sac, and due to retractions and distractions, the cervix dilates. The body of the uterus and the cervix have different structures and different innervations. In the area of the uterine body there is a longitudinal arrangement of fibers, and in the area of the isthmus and cervix it is circular. The body of the uterus is innervated by sympathetic fibers, and the cervix by parasympathetic fibers. Therefore, if the body of the uterus relaxes, the cervix closes (as happens during pregnancy). During childbirth, the muscles of the uterine body contract, and the muscles of the cervix relax, which contributes to the expulsion of the fetus.

During contractions, intrauterine pressure increases, and during pushing, intra-abdominal pressure increases.
Attempts occur reflexively due to irritation by the presenting part of the fetus of the nerve elements embedded in the cervix, pelvic floor muscles and parametric tissue.

Attempts occur involuntarily, but the woman in labor can regulate them to a certain extent (strengthen with tension and weaken with deep breathing).

A simultaneous increase in intrauterine pressure (contractions) and intra-abdominal pressure (pushing) promotes the advancement of the fetus in the direction of least resistance, i.e., into the small pelvis and further out.

Obstetrics and gynecology: lecture notes A. A. Ilyin

Lecture No. 4. Signs of fetal maturity, size of the head and body of a mature fetus

The length (height) of a mature, full-term newborn varies from 46 to 52 cm or more, averaging 50 cm. Fluctuations in the body weight of a newborn can be very significant, but the lower limit for a full-term fetus is the weight of 2500–2600 g. The average body weight of a mature, full-term newborn 3400–3500 g. In addition to the body weight and length of the fruit, its maturity is judged by other characteristics. A mature, full-term newborn has a well-developed subcutaneous fat layer; skin pink, elastic; the vellus cover is not expressed, the length of the hair on the head reaches 2 cm; ear and nasal cartilages are elastic; nails are dense, protruding beyond the edges of the fingers. The umbilical ring is located midway between the pubis and the xiphoid process. In boys, the testicles are lowered into the scrotum. In girls, the labia minora are covered by the labia majora. The child's cry is loud. Muscle tone and movements of sufficient strength. The sucking reflex is well expressed.

The head of a mature fetus has a number of features. It is the largest and densest part of it, as a result of which it experiences the greatest difficulties when passing through the birth canal. After the birth of the head, the birth canal is usually well prepared for the advancement of the fetal trunk and limbs. The facial part of the skull is relatively small, and its bones are firmly connected. The main feature of the cranial part of the head is that its bones are connected by fibrous membranes - sutures. In the area where the sutures join, there are fontanelles - wide areas of connective tissue. The lack of a strong connection between the skull bones is of great importance during childbirth. A large head can change its shape and volume, as sutures and fontanelles allow the bones of the skull to overlap each other. Thanks to this plasticity, the head adapts to the mother's birth canal. The most important sutures connecting the bones of the fetal skull are the following: the sagittal suture, passing between the two parietal bones; frontal suture - between the two frontal bones; coronal suture - between the frontal and parietal bones; lambdoid (occipital) suture – between the occipital and parietal bones. Among the fontanelles on the fetal head, the large and small fontanelles are of practical importance. The large (anterior) fontanel has a diamond shape and is located at the junction of the sagittal, frontal and coronal sutures. The small (posterior) fontanel has a triangular shape and is a small depression in which the sagittal and lambdoid sutures converge.

Head a full-term mature fetus has the following dimensions:

1) straight size (from the bridge of the nose to the occipital protuberance) – 12 cm, head circumference along the straight size – 34 cm;

2) large oblique size (from the chin to the occipital protuberance) – 13–13.5 cm; head circumference – 38–42 cm;

3) small oblique size (from the suboccipital fossa to the anterior angle of the large fontanelle) – 9.5 cm, head circumference – 32 cm;

4) average oblique size (from the suboccipital fossa to the border of the scalp of the forehead) – 10 cm; head circumference – 33 cm;

5) vertical, or vertical, size (from the top of the crown to the sublingual region) - 9.5–10 cm, head circumference - 32 cm;

6) large transverse size (the greatest distance between the parietal tubercles) – 9.5 cm;

7) small transverse size (distance between the most distant points of the coronal suture) – 8 cm.

Dimensions torso the fruits are as follows:

1) shoulder size (shoulder girdle diameter) – 12 cm, shoulder girdle circumference – 35 cm;

2) transverse size of the buttocks – 9 cm, circumference – 28 cm.

author A. A. Ilyin

From the book Obstetrics and Gynecology: Lecture Notes author A. A. Ilyin

From the book Propaedeutics of Childhood Illnesses by O. V. Osipova

author A.I. Ivanov

From the book Obstetrics and Gynecology author A.I. Ivanov

From the book Polyclinic Pediatrics: lecture notes author Notes, cheat sheets, textbooks "EXMO"

From the book Propaedeutics of Childhood Illnesses: Lecture Notes by O. V. Osipova

From the book Encyclopedia of Clinical Obstetrics author Marina Gennadievna Drangoy

From the book Children's Diseases. Complete guide author author unknown

From the book Planning a Child: Everything Young Parents Need to Know author Nina Bashkirova

From the book Harmonious Childbirth – Healthy Children author Svetlana Vasilievna Baranova

From the book Pregnancy: week by week. Consultations with an obstetrician-gynecologist author Alexandra Stanislavovna Volkova

Fertilization occurs in the ampullary section of the tube after the processes of sperm capacitation - the loss of surface glycoprotein antigens of the sperm head and its activation. Capacitation occurs in the vagina, uterus, and tubes as sperm advance.

A necessary condition for fertilization is the synchronicity of gametogenesis and ovulation. The time between ovulation and fertilization in women ranges from 12-24 hours. Of 100 ovulated eggs, 15 are not fertilized (physiological prezygotic elimination).

Statistical analysis of births in the countries of the USA, Western Europe and Australia showed that there are characteristic birth rate curves with a broad peak in the winter months, a slight rise in the summer and a decline in the spring and autumn. And conception often occurs in spring and autumn; anovulatory and hypoluteal cycles are more often observed in winter and summer. Seasonal variation in the frequency of certain types of congenital pathology in humans is explained by dissynchronization of ovulation and the process of oocyte maturation during the transition from anovulatory cycles to ovulatory cycles during the changing seasons of the year (Nikitin A.I. Aging of gametes and congenital pathology // Obstetrics and Gynecology. - 1981. - No. 3, 6-9).

The rhythm of gametogenesis and ovulation is determined by the duration of light stimulation. In Arkhangelsk, the minimum daylight hours are 3 hours 51 minutes (December 22), the maximum is 21 hours 21 minutes (June 22). The indirect action of light through the pineal gland causes 80-85% of menarche to appear in the first quarter of the year.

And pregnancy proceeds most favorably when conceived with an increasing daylight hours from 7 to 14 hours (February 10 - April 15) or a decreasing daylight hours from 14 to 7 hours (August 15 - November 15). Moreover, for primiparous women under the age of 24 years, the optimal period of conception is the first peak of fertility, which corresponds to menarche in the season - cumulation of fertility. For women over 28 years of age, the second seasonal peak of fertility is more optimal.

When conceiving during favorable periods of fertility, the frequency of pregnancy complications such as miscarriage, early and late toxicosis is reduced by 2-2.5 times.

Critical periods of pregnancy

Fertilization (40 hours)	embryogenesis (up to 9 weeks):	zygote-morula
implantation (1-2 weeks)		blastula
placentation (3-6 - 12-14 weeks)	histoorganogenesis (up to 12-14 weeks)
	fetogenesis:	functiogenesis (up to 18-24 weeks)
		intensive fetal growth systemogenesis (up to 37 weeks)
		childbirth

Up to 50% of zygotes die in the early stages of development and about 20% of diagnosed pregnancies end in spontaneous miscarriage, more than half of which are caused by lethal chromosome abnormalities.

Artificial termination of pregnancy causes a sudden and fundamentally different reaction from spontaneous abortion. Therefore, after an artificial abortion, the frequency of intrauterine death of fetuses, mainly males, increases in subsequent pregnancies.

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The processes of implantation and placentation depend on the decidual reaction of the endometrium. The active function of the placenta is formed by 14-16 weeks; by the end of pregnancy, the contact area of the placental villi is 8-12 m 3 . The placenta is the functional heart of pregnancy. The total blood flow in the intervillous space is 500-600 ml/min. Blood circulation in the intervillous space occurs slowly at low pressure (10 mm Hg), due to which effective metabolism occurs, and venous blood is discharged through the marginal sinus into the veins of the uterus. The placenta performs the functions of external respiration, excretory, nutritional, synthesis of fetal proteins, depositing, intrasecretory (synthesis of human chorionic gonadotropin, sex steroid hormones, relaxin, placental lactogen, trophoblastic b 1 -glycoprotein - TBG, a 2 -fertility microglobulin - AMGF, placental - a 1 - microglobulin - PAMG-1).

Alpha fetoprotein (AFP) is an embryo-specific protein in the amniotic fluid; its increase is observed in cases of neural tube developmental anomalies, congenital nephrosis, teratomas, gastrointestinal atresias, Turner, Down, Meckel syndromes, tetralogy of Fallot, etc., as well as in intrauterine fetal death.

Trophoblastic beta globulin (TBG) appears from the end of the first week of pregnancy (possibility of early diagnosis), increases as pregnancy progresses. Its decrease is observed in cases of non-developing pregnancy, moderate and severe gestosis and miscarriage.

Human placental lactogen (PLC) begins to be determined from 18-20 weeks of pregnancy. Its level decreases with gestosis, threat of miscarriage, and intrauterine fetal malnutrition. Its low content before birth predicts complications during childbirth and the postpartum period, and intrapartum fetal asphyxia.

Alpha 2-microglobulin fertility (AMHF) is secreted into the amniotic fluid. Specific outside of pregnancy for ovulation with a maximum increase towards the end of the cycle.

Placental alpha-1-microglobulin (PAMG-1) is found in amniotic fluid and decreases as pregnancy progresses. Relates to the processes of regulation of fetal growth. With gestosis, threat of miscarriage, malnutrition, there is a significant increase in the serum concentration of PAMG-1.

The placenta provides immune protection to the embryo and fetus, fixing antibodies and reducing cell and tissue immunity of the mother; its histagema barrier regulates the penetration of substances from mother to fetus and back.

The placental permeability index for drugs averages 50%, with wide fluctuations from 10 to 90-100%.

There is also paraplacental exchange due to the active function of the decidual, amniotic and chorionic membranes. Omnipotent fluid is formed by the epithelium of the amnion, and its average daily turnover is 12-15 liters. The amnion and chorion contain enzymes of nitrogen, carbohydrate and lipid metabolism, RNA, glycogen, mucopolysaccharides, proteins and amino acids. Glucose, urea, potassium, sodium, and calcium pass freely through the amnion and chorion.

Indicators of physical development of the fetus depending on the duration of pregnancy

Gestation period, weeks.	Fruit weight, g	Fetal growth, cm
12	40	8-9
16	120	16
20	300-320	24-26
24	500-600	28-31
28	1000	35
32	1600-1800	40-42
36	2500-2750	45-48
40	3500	50

Over 10 lunar months, the weight of the fetus increases compared to the weight of the zygote by 6 ´ 10 12 times.

Cumulative signs of fetal maturity

Height 48-50 cm, weight 3200-3500 g.

The chest is convex, the umbilical ring is between the womb and the navel.

The skin is pale pink, smooth, smooth, the subcutaneous layer is pronounced, remains of a cheese-like lubricant in the skin folds, vellus hair on the shoulders and upper back, nails extend beyond the fingertips, hair on the head up to 2 cm.

Ear and nasal cartilage are elastic.

The testicles are in the scrotum, the clitoris and labia minora are covered by the labia majora.

The movements are active, the eyes are open, the cry is loud, it takes the chest well.

Principles of a systematic approach to the study of the relationship between mother and fetus

Fetal-maternal relationships proceed in inextricable unity, while not so much the fetus adapts to its external environment (the mother), but rather the external environment itself is purposefully restructured for the optimal implementation of conditions that can ensure the fullest realization of genetic capabilities. A functional mother-placenta-fetus system is formed.

Systemogenesis is the selective development in embryogenesis of structures of different function and localization, which, when combined, form functional systems that provide vital manifestations of the developing organism.

The development of a particular organ of the fetus depends on the condition of this organ of the mother.

Biophysical profile of the fetus ( A.M. Vintrilers, 1983)

Non-stress test (NST)

Fetal respiratory movements (FRM)

2 b.	-	at least one episode of DDP lasting 60 seconds. or more in 30 minutes. observations
1 b.	-	at least one episode of DDP from 30 to 60 seconds. in 30 min. observations
0 b.	-	DDP less than 30 sec. or their absence in 30 minutes. observations
Fetal motor activity (YES)
2 b.	-	at least 3 generalized movements in 30 minutes. observations
1 b.	-	1-2 generalized movements in 30 minutes. observations
0 b.	-	absence of generalized movements for 30 minutes. observations
When comparing the mother's feelings about fetal movement with echography data, the agreement is 80-85%. Fetal movements are more intense in the evening, their number increases from 20 to 32 weeks of pregnancy; in the last 2 months of pregnancy, the number of fetal movements decreases. A decrease in the intensity of movements in case of disturbances in the fetal condition occurs 12-96 hours earlier than changes in the fetal ECG.
Fetal tone (FT)
2 b.	-	one episode or more of extension with a return to the flexion position of the spine and limbs in 30 minutes.
1 b.	-	at least one episode of extension with a return to flexion of either the limbs or the spine.
0 b.	-	limbs in an extended position
Amniotic fluid volume (AMF)
2 b.	-	waters are clearly defined in the uterus, the vertical diameter of the free area of water is 2 cm or more
1 b.	-	vertical diameter of free water area 1-2 cm
0 b.	-	close arrangement of small parts of the fruit, vertical diameter of the free area of water less than 1 cm
Degree of placenta maturity (PPM) - according to P.A. Urannum, 1979
2 b.	-	0, I, II degree of maturity of the placenta
1 b.	-	placenta along the posterior wall of the uterus and determining the degree of maturity is difficult
0 b.	-	III degree of maturity of the placenta

In the last two weeks of pregnancy and two weeks after birth, the newborn fetus experiences hypobiosis.With the morphological and functional readiness of all major organs and life support systems, it is noted extreme irritants: decreased physical activity, decreased heart rate, decreased intensity of metabolic processes, low O consumption 2 and CO 2 products , dominance of anaerobic glycolysis, acidosis, hypoglycemia, poikilothermia, immunological tolerance.

Hypobiosis is a protective mechanism that ensures the fetus’s body’s resistance to adverse environmental influences.

Characteristics of the full-term fetus. Definition of maturity.

The concept of fetal maturity is determined by a number of characteristic signs of its physical development. The concept of full-term fetus is determined by the length of its stay in the uterus from the moment of conception to birth.

Full term A fetus is considered to be born after 37 weeks of gestation with a body weight of 500 g or more (on average 3500 g) and a length of 35 cm or more (on average 50-52 cm). A live, full-term baby shows great activity, moves its limbs, and makes a loud cry.

A mature fetus has a fairly developed subcutaneous fat layer, pink skin color, dense cartilage of the ears and nose, hair on the head 2-3 cm long. The fluff is preserved only on the shoulder girdle in the upper back; The umbilical ring is located midway between the pubis and the xiphoid process. In boys, the testicles are lowered into the scrotum; in girls, the labia minora and clitoris are covered by the labia majora.

Signs of fetal maturity. The maturity of a newborn baby is judged by a combination of a number of signs.

1. The length (height) of a mature, full-term newborn is on average 50 - 52 cm (ranges from 48 to 57 cm), body weight is 3200 - 3500 g (ranges from 2600 to 5000 and above).

Length is a more constant value than body weight, so it more accurately reflects the degree of fetal maturity.

It should be noted that nowadays most children are born larger than a few decades ago. This is due to the improvement in material conditions and cultural level of the people of many countries. In accordance with this, the average body weight and height of newborns is greater than in previous years (average height 50 cm, body weight 3000 g).

The growth of the fetus is influenced by the mother's nutrition (with adequate nutrition, children are larger), the general regime of the pregnant woman, the gender of the child (the average body weight and height of boys is greater), the mother's age (in young and old children the weight of children is smaller), the number of previous births (the weight of the fetus increases during subsequent births), hereditary and other factors. Fetal growth slows down with many maternal diseases, especially severe ones. Retarded body weight and growth are associated with disturbances in the nutritional conditions and gas exchange of the fetus, intoxication, hyperthermia and other unfavorable factors that arise from maternal diseases.

Post-term babies are usually larger than full-term babies.

With immunological incompatibility for the Rh factor, diabetes mellitus, large children are often born with large body weight (sometimes height), which is due to the occurrence of pathological processes.

Newborns with a length of more than 47 cm are considered mature, those with a length of 45 cm and less are considered immature. Determination of maturity or immaturity of newborns with a length in the range of 45 - 47 cm is made in each case based on a particularly careful analysis of all signs. The conclusion about the maturity of such children is made by an obstetrician and a pediatrician jointly. In the absence of data on the growth of the newborn, his body weight is taken into account, and a newborn with a body weight below 2500 g is considered immature.

A mature newborn has a convex chest, the umbilical ring is located midway between the pubis and the xiphoid process.

The skin of a mature newborn is pale pink, the subcutaneous fat layer is well developed, and there are remains of a cheese-like lubricant on the skin; there is fluff only on the shoulders and upper back; The length of the hair on the head reaches 2 cm, the nails extend beyond the fingertips.

Ear and nasal cartilage are elastic.

In boys, the testicles are lowered into the scrotum; in girls, the labia minora and clitoris are covered by the labia majora.

The movements of a mature newborn are active, the cry is loud, the eyes are closed, and he takes the breast well.

Head of a mature fetus. The study of the shape and size of the fetal head is of particular importance in obstetrics. In the vast majority of births (96%), the head is the first to pass through the birth canal, making a series of sequential movements - turns.

The head, due to its density and size, experiences the greatest difficulty when passing through the birth canal. After the birth of the head, the birth canal is usually sufficiently prepared for the advancement of the torso and limbs of the fetus. The study of the head is important for the diagnosis and prognosis of labor: the location of the sutures and fontanelles is used to judge the mechanism of labor and its course.

The head of a mature fetus has a number of features. The facial bones are firmly connected. The bones of the cranial part of the head are connected by fibrous membranes, which determine a certain mobility and displacement in relation to each other. These fibrous membranes are called sutures. Small spaces where the sutures intersect are called fontanelles. The bones in the area of the fontanelles are also connected by a fibrous membrane. As the head passes through the birth canal, the sutures and fontanelles allow the bones of the skull to overlap each other. The bones of the skull bend easily. The structural features of the bones give the head plasticity; it can change shape, which is extremely important for its passage through the birth canal.

The fetal skull consists of two frontal, two parietal, two temporal and one occipital, sphenoid and ethmoid bones. In obstetrics, the following sutures are of particular importance (Fig. 25).

The sagittal (sagittal) suture connects the right and left parietal bones; in front the seam passes into the anterior fontanelle, in the back into the posterior one.

The frontal suture is located between the frontal bones; has the same direction as the arrow-shaped seam.

The coronal suture connects the frontal bones with the parietal bones and runs perpendicular to the sagittal and frontal sutures.

The lambdoid (occipital) suture connects the occipital bone with the parietal bones.

In the area where the seams join, there are fontanelles (spaces free of bone tissue). The anterior and posterior fontanelles are of practical importance.

The anterior (large) fontanel is located at the junction of the sagittal, frontal and coronal sutures and has a diamond shape. Four sutures extend from the anterior fontanel: anteriorly - frontal, posteriorly - sagittal, to the right and left - the corresponding sections of the coronal suture.

The posterior (small) fontanelle is a small depression in which the sagittal and lambdoid sutures converge. The posterior fontanelle is triangular in shape; Three sutures extend from the posterior fontanel: anteriorly - sagittal, to the right and left - the corresponding sections of the lambdoid suture.

It is important to know the following bumps on the fetal head: occipital, two parietal, two frontal.

Dimensions of the head of a mature fetus.

1. Straight size - from the glabella, glabella, to the occipital protuberance 12 cm. The head circumference corresponding to the straight size is 34 cm.

2. Large oblique size - from the chin to the occipital protuberance 13-13.5 cm. The head circumference corresponding to this size is 38 - 42 cm.

Small oblique size - from the suboccipital fossa to the anterior corner of the large fontanel 9.5 cm; The head circumference corresponding to this size is 32 cm.

The average oblique size is from the suboccipital fossa to the border of the scalp of the forehead 10 cm. The circumference of the head corresponding to this size is 33 cm.

The vertical, or vertical, size is from the top of the crown (crown) to the sublingual area 9.5 -10 cm. The circumference of the head corresponding to this size is 32 cm.

6. transverse size - the greatest distance between the parietal tubercles is 9.25 - 9.5 cm.

7. Small transverse size - the distance between the most distant points of the coronal suture is 8 cm.

Body dimensions.

1. The size of the shoulders is the diameter of the shoulder girdle 12 cm. The circumference of the shoulder girdle is 35 cm.

2. The transverse size of the buttocks is 9 - 9.5 cm. The circumference is 28 cm.