Physiology and weight of the premature child depends, on the one hand, on its age, on the other, on the cause of the premature labor. The extremes vary between 750 Gm. (1 lbs.) and 3000 Gm. (6 lbs.). According to Ahlfeld and Hecker, the averages of body weight and length in round numbers, are as follows: These figures have only an approximate worth, as can be seen from the following statistics of French writers, showing the widely varying weights of premature infants.
In case the average weight is less than that of a healthy foetus of the corresponding age, it is justifiable to conclude that a greater or less number of these observed children were debilitated or at least ill.
In every case one must bear in mind that the weight especially, (even more so than the body length) is individually extremely vari able; thus we have a type of children, usually from parents of slight stature, who are small in structure, and although they weigh only 2000 Gm. (41 lbs.) they are in no way debilitated and show no signs of prema turity. According to Pinard, we find of very small weight with such children.
It is otherwise with hereditary syphilis in which strikingly large placenta are found with the tiniest weaklings. The children of albu minuric and nephritic mothers are also small and puny and have been termed "spiders" by Pinard. The statistics of Berthod demonstrate how inadequate an aid the weight of the premature is for determining its age; these statistics include 4S children born at eight months or more, weighing less than 2000 Gm. (41 lbs.) and among these seven full term infants; also fifty-two infants born at less than eight months whose weight was more than 2000 Gin. (41 lbs.), and among these two born at six months. The body length may be taken as a reliable criterion.
Body Temperature and Energy sensi tiveness to low temperatures is peculiar to premature children and weaklings. The temperature of a healthy newborn infant falls a few tenths of a degree centigrade after birth, but ordinarily soon returns to normal. This is not the case with the premature, and especially not, with the debilitated premature child. In these cases the temperature falls steadily to 32° C. (90° F.) and even lower, unless the child is placed in an especially favorable environment. On an average the less the weight of the child and the more debilitated it is, the lower its tempera ture. The reasons for this lasting hypothermia—whether a primarily
deficient oxidation (Bonniot) or an inactivity of the thermo-regulative apparatus (nervous influence) as certain French authors are inclined to assume—remain unsettled.
After the initial drop, the temperature curve takes the form of a parabola. The longer the child is without artificial heat, the flatter the curve. A retarded rise, when in the incubator, is an unfavorable sign, just so an abrupt rise after a previously stationary, subnormal tempera ture. Also, premature children characteristically show an instability of body temperature in contrast to the slight nocturnal variations of the healthy young nursling. A deficient thermal regulation, which according to Babak is characteristic of all newborn infants, is found in an exaggerated degree in premature, debilitated children. Much energy is lost through increased loss of heat through the skin, on account of the relatively greater body surface of the premature child which also lacks adipose tissue. Added to this, these children lack, as do all newborn infants, the physical thermo-regulative capacity; whereas the chemical thermal regulation (increase in oxidation processes), which, in these children and especially the debilitated ones, is, without this, at a very low point, becomes taxed beyond its capacity. This leads to changes in the alkalinity of the blood (lowered to one-quarter the nor mal) and to the deposition of waste products and toxins in the body (Charrin, Guillemonat, Levaditi). Pfaundler, examining debilitated premature children, found the actual reaction of the blood to be acid. (The concentration of the OII–ions smaller than that of the II-ions.) A more favorable balance of energy, showing a certain excess of energy necessary for increase in size and weight, is only possible by lowering the loss of heat by wrapping the child in a non-conductor of heat, by hot-water bottles or by raising the temperature of the en use of the incubator. •When one considers the diffi culty of nourishing premature children, and their deficient assimilation, it becomes plain that the balance of energy very readily becomes nega tive; that is, the child loses ground. More exact knowledge concerning the dynamic exchange in premature or debilitated children is not at hand.