[Comparative analysis of growth and sexual maturation in girls of Santa Rosa (La Pampa) and La Plata (Buenos Aires), Argentina].

The aim of this study was to analyze growth in relation to menarche in girls from two Argentinean urban populations. We performed a comparative-descriptive cross sectional study in 2474 schoolchildren between 8.0 and 16.9 years old from Santa Rosa (SR) and La Plata (LP) cities. We registered the presence of menarche and anthropometrics variables of body weight, total and sitting heights, arm circumference, triceps and subscapular skinfolds. Body mass index, subscapular/triceps index and muscle and fat arm areas were calculated. The study group was divided into 4 groups according to the city and menarche. The socio-environmental structured survey indicated significant differences between cities with these variables: tenure status, building materials and services, health care coverage, cash assistance, educational level and parents' occupation, therefore establishing a higher welfare in youngsters of SR. Menarche at a mean age of 12.7 years old was more prevalent in SR (40.6%) than in LP (33.7%) (c2 = 12.9; p < 0.01). The ANOVA indicated significant differences between cities in total and sitting heights and muscle area (p < 0.01), body weight and arm circumference (p < 0.05) which were generally held in the post hoc comparison by age in pre-menarche and post-menarche groups. The presence of a small body size at the expense of lowering in: total height, muscle area and leg length in LP youngsters, associated with a lower prevalence of menarche in this city, it would represents the adaptive cost of a lower welfare environment.