The digestion of premature infants is naturally not as strong as that of infants born at term. Very little is positively known, but the consensus of opinion goes to show that in the majority of cases the tolerance for sugar is greater than that of either the proteins or fats. The loss of heat is relatively greater in proportion to its surface area in small than in large bodies. This is a well-known fact, hence the premature baby must require more food in proportion to its weight than the baby who is born at the normal time. Then, too, as the premature infant is thinner he does not keep warm like the older infant, and this must be taken into consideration in feeding him. Breast milk is of course by far the best food for such babies, not only because its constituents are in a more available form for the feeble digestive organs, but because the mother’s milk furnishes a resistance which is lacking in even the most carefully modified of milk formulas.
Energy Requirements of Premature Infants.—Experiments made upon premature infants have proved that the caloric needs of these babies are greater than in the case of full-time babies; that is, they require more per kilogram of body weight. According to Morse,[79] “most premature babies need 120 calories per kilogram of body weight. But there are many exceptions, some thriving on as little as 70 calories per kilogram. No attempt should be made to reach 120 calories per kilogram during the first few days. Thirty calories per kilogram is as much as is wise to give in the first 24 hours of feeding. This amount should be gradually increased each day, watching carefully for symptoms of indigestion and diminishing it if these appear. One hundred and twenty calories per kilogram can be given in about 10 days.”[80]
Necessary Dilution.—Even breast milk must be diluted with an equal amount of water or a 3% sugar solution. The amount of milk should be increased and the amount of dilution decreased until the undiluted breast milk is given in four or five days. Like older babies, the next best food for premature babies is the properly modified cow’s milk, but the utmost care will have to be observed, as these babies are more easily upset than older and stronger ones.
Premature Infant Feeding.—The following method of feeding may be suggested, keeping in mind that it is an easy matter to increase the strength of a mixture if the baby shows the need of such an increase. The premature baby is rarely strong enough to take the breast.
Method of Administering Milk.—The most satisfactory method of administering the food in such cases is by means of the Brick feeder, which consists of a graduated glass tube, open at either end. On the small end is placed a small nipple like those seen on medicine droppers; this one is perforated and goes into the mouth of the baby. A large rubber finger cot is attached to the other end of the tube. The milk is forced into the mouth by pressing the finger cot. In case the infant is too feeble even for this method of feeding, the desired amount is dropped into the mouth from a medicine dropper; 5 c.c. (about 1 dram or 1 teaspoonful) of diluted milk being given at each feeding. This amount is increased gradually from day to day.
Whey Mixtures.—Whey mixtures have been found to meet the needs of premature infants more efficiently than ordinary mixtures. As the proteins in whey are in a more digestible form, they throw less work on the immature digestive apparatus. As a rule the casein and whey are in proportion of 1:1.
The following formulas[81] show the amounts in which the food constituents are combined and are suitable for premature babies:
| Fat | 1.00% |
| Milk sugar | 4.00% |
| Total proteins | 0.25% |
| Lime water | 25% of cream and milk mixture |
or
| Fat | 1.00% |
| Milk sugar | 4.50% |
| Total proteins | 0.50% |
| Lime water | 25% of cream and milk mixture |