This document discusses nutrition and health promotion during pregnancy and breastfeeding. It notes that breast milk provides sufficient nutrition for infants to double their birth weight by 6 months and contains over 200 substances that vary depending on the woman and stage of lactation. Breast milk from women who deliver premature infants contains higher levels of calories, fats, proteins, and immune factors. The document outlines nutritional guidelines and additional calorie and nutrient needs for lactating women, including calcium, iron, folic acid, vitamins, fluids, and snacks. It discusses factors that can influence breast milk composition and causes of low milk supply.