Experimental details

1. Subjects
Twenty infants were studied (13 male and 7 female), as part of a longitudinal investi gation on maternal nutrition and lactation. All were breast-fed up to the sixth month, and 16 were still being breast-fed by the end of the seventh month. Fifteen of the mothers were recruited through the Cambridge Maternity Hospital, and five via the National Childbirth Trust.

2. Anthropometry
The babies' weights, lengths (using a Harpenden Infant Measuring Table), and triceps skin-fold thicknesses (using Holtain callipers) were measured at monthly intervals.

3. Dietary Intakes
From four weeks of age, breast-milk intakes were measured in the home on four consecutive days each month by test-weighing, using Salter Baby weigher Model 40 Scales, after the mothers had received careful instruction in this technique. All other food and drink, including medicaments such as gripe water and "vitamin syrups," were also quantitatively recorded by the mothers for the same four days. First, supplementary foods introduced were usually proprietary cereal preparations, "baby dinners," or foods from the rest of the family's supply; infant formulas based on cow's milk were never given. Energy intakes were calculated using food composition tables and from information provided by manufacturers. The energy content of breast milk was taken to be 69 kcal/100 9, the average value found in a recent national survey of British mothers'milk.

FIG. 1. Total Energy Intake of 20 Babies Compared with the Recommendations of WHO/FAD and the United Kingdom's DHSS (Values are mean + S.E.M.)