~Habits of Mother.~--The mother must be taught how to efficiently nurse her baby; she must keep in mind that upon her good health and temperate habits depend the health and comfort of her baby. It devolves upon her to provide food efficient in quality and quantity. To do this, her own diet must be simple and wholesome. The nursing mother must remember that she has to provide, not only for her own maintenance and energy requirements, but also for the infant whose fuel requirements are ever demanding more food to provide for its rapid growth. ~Food and Its Relation to Milk.~--It is believed that two calories of food extra are necessary to produce one calorie of milk, and since a month-old baby requires 2-1/3 ounces of mother's milk to every pound of his body weight, and one ounce of mother's milk will yield 20 calories, it is clearly seen that the mother will have to increase her diet to cover the requirements of the baby. For example, if the baby weighed 12 pounds, he would require 28 ounces of milk in 24 hours, or 560 calories. Thus if it requires two calories of extra food to make one calorie of milk, the mother's diet would have to provide 1,120 calories extra, or about as much food as would fulfill the needs of a laboring man, 3,000 to 3,500 calories, even if she were doing practically no actual work; while if she were actively employed and doing a certain amount of physical labor, her rations would have to approximate those of a man doing heavy muscular work (about 3,500 to 4,000 calories per day).[66]