[Growth of exclusively breast-fed Chilean infants in relation to new 1994 WHO Reference Charts].

The aim of this study was to evaluate the growth of Chilean infants from medium-to-low socioeconomic status fed according to the current WHO guidelines. Growth pattern was compared to a recent reference chart published by WHO for infants, and the NCHS/WHO growth standards. The source of information was a nation-wide infant feeding survey conducted in 1993. From this database, infants aged 1-12 month +/- 5 days, with exclusive breast feeding until the fourth or sixth month were selected (939 males, 940 females). The weight-for-age z-score (WAZ), and the height-for-age z-score (HAZ) were calculated using both the NCHS/ WHO and the new WHO reference growth charts. At each month of age, WHZ and HAZ results were grouped in the following categories: < = -2.0; -1.9 to -1.0; 0 +/- 0.9; 1.0 to 1.9; and > = 2.0. Observed WAZ at the first month of age was below the new WHO reference chart (0.32 z-score), increasing up to 1.29 z-score at the tenth month. The HAZ results were lower the WHO reference chart throughout the period studied, although a trend to improved values was noted during the second semester (F = 6.01 p < 0.001). Growth pattern of the studied group was more similar to the NCHS/WHO chart than the new chart proposed by WHO. As a consequence, the new WHO reference chart identifies a higher proportion of the infants as having a subnormal nutritional status during the first semester of life, compared to those classified in this category by the NCHS/WHO standards (p < 0.001). This can be a factor for the introduction of complementary foods early in life. The relative homogeneity of the population used as source of the WHO reference chart may limit it use in developing countries.