The Embryo : Part 3

The Prospective Mother: A Handbook for Women During Pregnancy
by J. Morris Slemons

(Page 6 of 18)

At the end of the fifth month, the weight of the fetus is from nine to ten ounces; whereas an average infant when born at the expiration of the full term of pregnancy, that is, with the completion of the tenth month, weighs about seven pounds. The fetus, therefore, acquires roundly ninety per cent, of its weight during the second half of pregnancy, which clearly indicates that Nature reserves this period of gestation for the fetus to increase in size, a phenomenon less mysterious but no less important than the evolution of the embryo.

Nothing is more valuable than the weight in affording an indication as to whether a prematurely born infant may be reared. It is unusual to raise a child weighing less than four pounds, which corresponds approximately to the end of the eighth lunar month of development (a trifle more than the seventh calendar month). After this time, the prospect of living becomes greater in proportion to the nearness with which the infant has approached maturity. No truth exists in the widespread belief that the seventh-month child is favored above that born later but before the natural end of pregnancy. Experience has taught that the probability of success in rearing the child increases rapidly after the seventh month. This is reasonable on the following somewhat theoretical grounds. The digestive organs later attain a higher state of perfection, and are better prepared to carry on their work satisfactorily. Moreover, the gradual deposition of fat beneath the skin during the last two months of pregnancy materially assists in fitting the child for the conditions met with in the external world, since the fat affords a barrier against the escape of heat generated within the body, making it much easier to keep the child's temperature at the normal point. Even other more technical reasons could be given to demonstrate the error of the superstition regarding the seventh-month child - a conviction endorsed by medical men hundreds of years ago and as yet not discarded by the laity.

When pregnancy has reached "term," the child, having completed its prenatal development, is ready to cope with conditions as they exist in the external world. At term the average child is twenty inches long and weighs 7 1/7 pounds (3,250 grams). The length is remarkably constant; but the weight, as is well known, is often somewhat above or below the average figure. In a general way, smaller children occur in the first than in subsequent pregnancies, and, moreover, may be expected when the mother is a small woman, or poorly nourished, or has worked hard during her pregnancy. On the other hand, a tendency to bear large children is present when the opposite conditions prevail. It is not unusual to see infants weighing eight or nine pounds at birth, but babies of more than ten pounds are rare, and the fabulous, though not infrequent, reports of fifteen and twenty-pound infants are probably not based upon actual weighings, but upon the impression of someone who has merely seen the child or perhaps guessed the weight from lifting it.

Although the fetus frequently changes its position during the earlier months of pregnancy, generally by the beginning of the tenth lunar month it has assumed a permanent posture. It has then reached such a size that it can best be accommodated in the cavity of the uterus if its various parts are folded together so as to give the fetus an ovoid shape. To secure this form its back is arched forward, and its head bent so that its chin touches its chest; its arms are crossed just below the head, its legs raised in front of the abdomen, and its knees doubled up. In this form the fetus occupies the smallest possible space.

With relation to the mother the position of the child, for several weeks before birth, is one in which its long axis is parallel to the long axis of her body. This remains true no matter whether the head or the buttocks are to precede at the time of birth. In ninety-seven out of a hundred cases, however, the head lies lowermost and consequently is the first portion of the child to be born. The opposite position, in which the head is the last portion born, is, even with the most skillful treatment, somewhat more serious for the infant, though not for the mother.

The Newborn Infant. The baby at birth is not a miniature man. As compared with an adult its head and abdomen are relatively large, its chest relatively small; its limbs are short in proportion to the body; and at first glance it appears to have no neck at all. The middle point of a baby's length is situated about the level of the navel, whereas in a man the legs alone represent approximately half his height. The changes after birth consist chiefly in growth; but not altogether, since at least one organ, the thymus gland, becomes smaller and completely disappears during childhood, and other organs, especially the liver, are proportionately smaller in the adult than in the infant.

The body of the infant also differs from that of the man in possessing greater softness and flexibility. These qualities depend upon the nature of its skeleton, which is composed of more bones than later in life, when several have fused together to form one to give the mature body a more rigid frame. Furthermore, the individual bones are not so firm, consisting of an elastic material called cartilage, so that some movements which in an adult would cause such serious injuries as fractures and dislocations are perfectly harmless to a newborn child.

The legs are not only short in proportion to the body but are always curved, and the feet are held with the soles directed toward one another, a position clearly abnormal in the adult. But every mother should know that these are natural conditions in the infant, and are the result of the posture of the child before birth. They soon straighten out. The bowed legs of an adult are of an entirely different origin, resulting from a disturbance of nutrition in infancy called rickets.

A small amount of short wooly hair is usually found over the back of a newborn infant. More conspicuous, however, is the presence there of a gray, fatty substance which, though always more abundant over the back, is at times distributed over the whole body; rarely is it entirely absent. The material, technically named the vernix, is the product of the glands in the skin and is a perfectly normal secretion. After its removal, which is readily accomplished by greasing the infant with lard or vaselin before giving the initial bath, it never reappears.