Lecture number 4. Signs of fetal maturity, the size of the head and body of a mature fetus

The length (height) of a mature full-term newborn ranges 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 2500-2600 g. The average body weight of a mature full-term newborn 3400-3500 g. In addition to body weight and length of the fetus, its maturity is also judged by other signs. A mature full-term newborn has a well-developed subcutaneous fat layer; skin pink, elastic; the vellus cover is not pronounced, 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 in the middle of the distance between the womb and the xiphoid process. In boys, the testicles are descended into the scrotum. In girls, the small labia are covered with large ones. The cry of a child 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 difficulty in passing through the birth canal. After the birth of the head, the birth canal is usually well prepared for the advancement of the trunk and limbs of the fetus. 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 of ​​\uXNUMXb\uXNUMXbthe connection of the seams there are fontanelles - wide areas of connective tissue. The absence of a strong connection of the bones of the skull among themselves is of great importance in the process of childbirth. A large head can change its shape and volume, as the sutures and fontanelles allow the bones of the skull to overlap each other. Due 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 two frontal bones; coronal suture - between the frontal and parietal bone; lambdoid (occipital) suture - between the occipital and parietal bones. Among the fontanelles on the head of the fetus, large and small fontanelles are of practical importance. The large (anterior) fontanel is diamond-shaped 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 meet.

Head full-term mature fetus has the following dimensions:

1) direct size (from the bridge of the nose to the occiput) - 12 cm, head circumference in direct size - 34 cm;

2) large oblique size (from the chin to the occiput) - 13-13,5 cm; head circumference - 38-42 cm;

3) small oblique size (from the suboccipital fossa to the anterior angle of the large fontanel) - 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) sheer, 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 largest distance between the parietal tubercles) - 9,5 cm;

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

dimensions torso fruit are as follows:

1) the size of the shoulders (diameter of the shoulder girdle) - 12 cm, the circumference of the shoulder girdle - 35 cm;

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

Author: Ilyin A.A.

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