The shape of the baby’s head is sometimes distorted at birth, being so elongated from chin to occiput as to give the parents deep concern. But they may be confidently assured that in the course of a few days the head will assume the lovely rounded contour, so characteristic of babyhood. The temporary deformity is caused by a moulding and overlapping of the bones of the skull as it is forced through the birth canal, and sometimes also to a collection of fluid under the scalp, called the caput succedaneum, and which, too, is due to pressure during birth. Both the anterior and posterior fontanelles may be felt at birth.
Growth and Development. The progress during the first year, of average, normal babies who are satisfactorily nourished and cared for, is fairly uniform and the accepted average is suggested by the following schedules which are based upon observations made upon a large number of normal, healthy infants.
Weight. The average baby boy weighs at birth, 7¼ to 7½ pounds and girls a little less, as a rule. There is an initial loss of from six to ten ounces during the first week, through body waste and the passage of meconium and urine, before the full amount of nourishment is taken and assimilated, large babies losing more than small ones. (Chart [5].) From this time the gain is usually from four to eight ounces, each week, during the first five months, after which it is only about half as rapid, or at the rate of from two to four ounces weekly. At six months, therefore, the average baby weighs from fifteen to sixteen pounds, or double the normal birth weight of 7½ pounds, and at twelve months, from twenty to twenty-two pounds, or three times the average birth weight. The weight is perhaps the most valuable single index to the baby’s condition, that we have, but at the same time, it must be remembered that a baby whose food is rich in carbohydrates may be of normal weight, or over, but be incompletely nourished and very susceptible to infection. Other babies who are small and seem to gain unsatisfactorily are sometimes very well and vigorous. And very commonly there are periods in the lives of entirely normal babies when there is little or no gain in weight. This may occur during the period from the seventh to the tenth month, for example, or during very warm weather. But the baby’s weight should be watched carefully, for a loss or prolonged failure to gain may be an evidence of faulty nutrition or disease.
Chart 5.—Weight chart showing average weekly gain during first year of life.
Height. The average height at birth is 20 inches, though boys may measure a little more and girls a little less; at six months, 25 to 25½ inches and at one year, 28 to 29 inches.
Head and Chest. The circumference of the head and chest are about the same at birth, the chest being possibly a little smaller. Both measure about 13½ inches, increasing gradually to about 16½ inches at six months and 18 inches at the end of the first year.
Fontanelles. The posterior fontanelle usually closes in six or eight weeks but the larger, anterior fontanelle is not entirely obliterated until the baby is eighteen or twenty months old. Closure of the fontanelles is usually late in rickets, cretinism and hydrocephalus and early in cases of malnutrition and microcephalus.
Teeth. Although it occasionally happens that a baby has one or two teeth at birth, the average infant has none until the sixth or seventh month, when the two lower, central incisors appear. After a pause of a few weeks the two, upper, central incisors appear, followed by the two lateral incisors in the upper jaw. At the end of the first year, therefore, the average baby has six teeth, or eight, if the lower, lateral incisors have come through by the first birthday, as they sometimes do. (Fig. [148].) This is the usual course of dentition during the first year, but there are wide variations among entirely well and normal babies, the first tooth sometimes not appearing before the tenth, eleventh or even twelfth month. But as a rule if no teeth are cut by the time the baby is a year old, it is regarded as an evidence of faulty nutrition, perhaps bordering on rickets.
The baby who is properly fed and cared for cuts his teeth with little or no trouble, in spite of the widely current belief that a teething baby is a sick baby. We have no way of estimating the number of babies who die needlessly from infections and digestive disturbances because of this fallacious conviction. For if the baby is sick while teething, the disturbance is all too frequently accepted as a normal occurrence and nothing is done until too late.