Referencias de índice de masa corporal. Precisión diagnóstica con área grasa braquial en escolares argentinos / Body mass index references. Diagnostic accuracy with the upper-arm fat area in Argentine schoolchildren

El índice de masa corporal (IMC) es una eficaz herramienta para detectar la sobrecarga ponderal en niños y adolescentes, asociado a la adiposidad corporal. Objetivo. Analizar la concordancia, sensibilidad y especificidad de tres referencias internacionales de IMC/edad (OMS, IOTF y CDC) para diagnosticar el exceso ponderal y conocer su precisión diagnóstica para identificar el exceso de adiposidad con relación al área grasa braquial (AGB) en población infanto juvenil de Argentina. Materiales y métodos. Se realizó un estudio multicéntrico, descriptivo-comparativo y transversal entre 2003 y 2008, en 22.658 niños y adolescentes argentinos de 4 a 13 años de edad. A partir del peso, talla, circunferencia del brazo y pliegue tricipital, se calcularon IMC y AGB. Se analizó la concordancia, sensibilidad y especificidad de referencias de IMC/edad (OMS, CDC, IOTF) y la precisión diagnóstica (curvas ROC) para identificar exceso de adiposidad, a partir del AGB, así como el punto de corte óptimo (PCO). Resultados. Las tres referencias tuvieron buena concordancia. La mayor sensibilidad correspondió a OMS y la mayor especificidad a IOTF. El área bajo la curva (ABC) fue mayor en Z-IMC/IOTF en varones y en Z-IMC/OMS en mujeres. Los PCO mostraron discrepancias, siendo mayores con OMS. Conclusión. Las tres referencias muestran similar precisión diagnóstica para detectar alta reserva calórica, con puntos de corte óptimo para las puntuaciones Z-IMC menores a 2 Z scores. Esto resulta relevante para la identificación de exceso de adiposidad en poblaciones, en relación con la implementación de políticas públicas de prevención de enfermedades crónicas no transmisibles(AU)

The body mass index (BMI) is an effective tool to detect weight overload in children and adolescents, associated with body adiposity. Objective. To analyze the concordance, sensitivity and specificity of three international BMI/age references (WHO, IOTF and CDC) to diagnose excess weight and to know their diagnostic accuracy to identify excess adiposity in relation to the brachial fat area (BFA) in Argentine child-youth population. Materials and methods. A multicenter, descriptive- comparative and cross-sectional study was carried out between 2003 and 2008 in 22.658 Argentine children and adolescents between aged 4 to 13 years. From the weight, height, arm circumference and tricipital fold, BMI and BFA were calculated. The concordance, sensitivity, and specificity of BMI / age references (WHO, IOTF, CDC,) were analyzed and the diagnostic precision (ROC curves) to identify excess adiposity, from the BFA, as well as the optimal cut-off point (OCP). Results. The three references had good agreement, the highest sensitivity corresponded to WHO and the highest specificity to IOTF. The area under the curve (AUC) was greater in Z-BMI/IOTF in men and in Z-BMI/WHO in women. The OCPs showed discrepancies, being higher with WHO. Conclusion. The three references show similar diagnostic accuracy to detect high caloric reserve, but with cut-off points for Z-BMI scores less than 2 Z scores. This is relevant for the identification of excess adiposity in populations in relation to the implementation of public policies for the prevention of chronic non-communicable diseases(AU)

Excess weight and thinness over two decades (1996-2015) and spatial distribution in children from Jujuy, Argentina.

BACKGROUND: The increase of excess weight around the world is progressive and sustained in children. This is the most prevalent form of malnutrition in this population and they represent the major public health problem in developed and developing countries. The aim of this study was to analyze the magnitude of change in thinness and excess weight prevalence in 4-7 years-old schoolchildren from Jujuy (Argentina), between 1996 and 2015 and to examine the association according to sex and school location. METHODS: Cross-sectional study. Data was obtained from databases of School Health programs and it is representative of the city school population. For the analysis, 31,014 schoolchildren between 4 and 7 years old were evaluated, 20,224 from the first period (1996-2001) and 10,790 from the second (2010-2015). The city was partitioned in three different areas determined by the rivers that cross it. Nutritional status was determined by BMI for age with the criteria suggested by the International Obesity Task Force. The percentage of malnutrition change between periods was calculated and a binomial regression model was adjusted. RESULTS: Between periods, a significant (p-value< 0.0001) increase in the prevalence of overweight from 15.1% (CI 14.6-15.6%) to 18.1% (CI 17.4-18.8%) and obesity from 5% (CI 4.7-5.3) to 10.7% (CI 10.1-11.3%), and a decrease of thinness prevalence from 6.3% (CI 6.0-6.7%) to 4.7% (CI 4.3-5.1%) were observed. The percentage of change in the prevalence of obesity was very high in all areas and in both sexes (103.5% girls; 125.6% in boys), being higher in the south for girls (122.4%) and in the north for boys (158.8%). Besides, being a boy was inversely associated with the presence of excess weight and, as the age increases, the presence of obesity does it too. By analyzing the effect of the school location, the south and north zones had an inverse association with the presence of obesity. The period has a direct association with the presence of excess weight. CONCLUSION: The study contributes with valuable information on the magnitude of the increase in obesity in schoolchildren and suggests a possible correlation with sex and spatial distribution in the capital city of Jujuy.

Dyslipidemia in schoolchildren with excess weight from Jujuy assessed by the program of school health / [Dislipemias en escolares jujeños con exceso de peso evaluados por el programa de salud escolar.]

Background: Excess weight (EW) and alterations in lipid metabolism constitute risk factors for cardiovascular disease in adults and children. Prevalence of dyslipidemia in schoolchildren from Jujuy with EW is analyzed in this study. Methods: Cross-sectional descriptive study of 891 schoolchildren 10-14 years old (367 girls; 524 boys) from the province of Jujuy (Northwestern Argentina). Prevalence of dyslipidemia for Overweight (OW) and Obesity (OB) were calculated, according to the International Obesity Task Force cut-off points. Prevalence of lipid alterations were analyzed and 7 dyslipidemic profiles were established. Comparisons and associations between variables were analyzed by Chi-square test. Crude and adjusted odds ratio were estimated from a logistic regressions. Results: Regardless of sex and nutritional status, 13.7%, 21.8%, and 16.5% of schoolchildren showed high values of total cholesterol, triglycerides, and LDL cholesterol, respectively, and 20.3% had low HDL cholesterol. Significantly higher values of HDL cholesterol were found in OW, and of triglycerides in OB. A significant association was recorded between OB and high triglycerides. Schoolchildren with OB have a 54% more chances of showing at least one lipid alteration. Conclusion: EW, and especially OB, constitutes an important risk factor in the development of dyslipidemia in schoolchildren from Jujuy.

Introducción: El exceso de peso (EP) y las alteraciones del metabolismo lipídico constituyen factores de riesgo de enfermedad cardiovascular en adultos y en niños. En este estudio se analiza la prevalencia de dislipemias en escolares jujeños con EP. Población y métodos: Estudio descriptivo, de corte transversal de 891 escolares entre 10-14 años (367 mujeres; 524 varones) de la provincia de Jujuy (Noroeste de Argentina). Se calcularon las prevalencias de dislipemias para Sobrepeso (SP) y Obesidad (OB), determinados según puntos de corte de la International Obesity Task Force. Se analizaron las prevalencias de alteraciones lipídicas y se establecieron 7 perfiles dislipemicos. Las comparaciones y asociaciones entre variables se analizaron con Chi cuadrado. Se estimaron odds ratio crudos y ajustados a partir de una regresión logística. Resultados: Independientemente del sexo y del estado nutricional el 13.7%, 21.8% y 16.5% de los escolares presentaron colesterol total, triglicéridos y colesterol LDL alto, respectivamente y el 20.3% colesterol HDL bajo. Se observaron valores significativamente más elevados de colesterol HDL en SP y de triglicéridos en OB. Se registró asociación significativa entre OB y triglicéridos altos. Los escolares con OB exhiben 54% más de chances de presentar al menos una alteración lipídica.. Conclusión: El EP, y sobre todo la OB, constituye un factor de riesgo importante para el desarrollo de dislipemias en escolares jujeños

CONSANGUINITY BY RANDOM ISONYMY AND SOCIOECONOMIC DEVELOPMENT IN ARGENTINA: A POPULATION STUDY.

In human populations various flexible, labile and interdependent structures (genetic, demographic, socioeconomic) co-exist, each of which can be organized in an hierarchical order corresponding to administrative entities. The relationship between consanguinity, as estimated by random isonymy (F ST), and socioeconomic conditions was analysed at different levels of political and administrative organization in Argentina. From the surnames of 22,666,139 voters from the 2001 electoral roll, F ST was estimated for 510 Argentinian departments. Using a principal component analysis, a Socio-Demographic and Economic Indicator (SDEI), summarizing the effect of 22 socioeconomic and demographic variables at the departmental level, was computed. The relationship between departmental F ST and SDEI values was analysed for the whole nation and within regions using multiple regression analysis. The F ST presented a clinal distribution with the highest values in the north and west of the country, while SDEI expressed the opposite behaviour. A negative and significant correlation was observed between F ST and SDEI, accounting for 46% of the variation in consanguinity in Argentina. The strongest correlations of F ST with SDEI were observed in the Central, Patagonia and Cuyo regions, i.e. those with the highest values of SDEI and lowest values of F ST.

SUBSCAPULAR AND TRICEPS SKINFOLDS REFERENCE VALUES OF HISPANIC AMERICAN CHILDREN AND ADOLESCENTS AND THEIR COMPARISON WITH THE REFERENCE OF CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC).

INTRODUCTION: the assessment of the skinfold thickness is an objective measure of adiposity. Therefore, it is a useful tool for nutritional diagnosis and prevention of metabolic risk associated with excess fat in chilhood and adolescence. OBJECTIVE: to provide percentiles of subscapular and triceps skinfolds for Hispanic American schoolchildren and compare them with those published by the Centers for Disease Control and Prevention (CDC) from United States, that it have been commonly used as a reference in most of these countries. METHODS: subscapular and triceps skinfolds were measured in 9.973 schoolchildren 4-19 aged from Spain, Argentina, Cuba, Venezuela and Mexico with Holtain caliper with 0.2 mm accuracy. Percentiles were obtained with the LMS statistical method and were presented in tables divided in stages of 6 months and in curves graphics. The difference between Hispanic American and CDC mean values were provided for P3, P50 and P97 in mm and also were graphically represented. RESULTS: skinfolds measurements obviously increased with age in both sexes but, in boys, this increase is much more marked in highest percentiles between 8 and 13 years; this maximum is reached earlier than what occurs in CDC reference. In both sexes, all percentiles analized in Hispanic American schoolchildren were higher than the CDC reference except P97 up to 10 or 13 years that was notably smaller. CONCLUSIONS: the skinfolds percentiles of Hispanic American children and adolescents differ from CDC that are usually used as reference. The values of subscapular and triceps skinfolds provided in this study, could be applied to populations of a similar ethnic background, especially in comparative studies of body composition.

Introducción: la evaluacion del grosor de los pliegues subcutáneos es una medida objetiva de la adiposidad. Es por tanto una herramienta útil para el diagnóstico nutricional y la prevención del riesgo metabólico asociado al exceso de grasa en la infancia y adolescencia. Objetivo: proporcionar valores percentilares de los pliegues adiposos subcutáneos subescapular y tricipital para escolares hispanoamericanos y compararlos con los valores publicados por los Centros para el Control y Prevención de Enfermedades (CDC) de los Estados Unidos, que comunmente se emplean como referencia en estos países. Métodos: se midió el pliegue subescapular y tricipital en 9.973 escolares entre 4 y 19 años procedentes de España, Argentina, Cuba, Venezuela y México con un calibre Holtain de 0,2 mm de precisión. Los percentiles fueron calculados mediante el método estadístico LMS y presentados en tablas divididas en intervalos de seis meses y en gráficos de curvas. La diferencia entre los valores medios hispanoamericanos y los valores del CDC se muestran para el P3, P50 y P97 en mm, y también gráficamente. Resultados: las medidas de los pliegues subcutáneos se incrementan obviamente con la edad pero, en niños, este incremento es mucho más marcado en los percentiles superiores entre los 8 y 13 años; este máximo es alcanzado antes que en la referencia del CDC. En ambos sexos, todos los percentiles analizados fueron superiores en los escolares hispanoamericanos, exceptuando el P97 por encima de los 10 o 13 años, donde resultó notablemente inferior. Conclusiones: los percentiles de pliegues adiposos de los niños y adolescentes hispanoamericanos difieren de la referencia del CDC. Los valores del pliegie subescapular y tricipital proporcionados en este estudio podrían ser aplicados en poblaciones de similar origen étnico, especialmente en estudios comparativos de la composición corporal.

Subscapular and triceps skinfolds reference values of Hispanic American children and adolescents and their comparison with the reference of Centers for Disease Control and Prevention (CDC) / Valores de referencia para los pliegues adiposos subescapular y tricipital de niños y adolescentes hispanoamericanos y su comparación con la referencia de los centros para el control y prevención de enfermedades (CDC)

Introduction: the assessment of the skinfold thickness is an objective measure of adiposity. Therefore, it is a useful tool for nutritional diagnosis and prevention of metabolic risk associated with excess fat in chilhood and adolescence. Objective: to provide percentiles of subscapular and triceps skinfolds for Hispanic American schoolchildren and compare them with those published by the Centers for Disease Control and Prevention (CDC) from United States, that it have been commonly used as a reference in most of these countries. Methods: subscapular and triceps skinfolds were measured in 9.973 schoolchildren 4-19 aged from Spain, Argentina, Cuba, Venezuela and Mexico with Holtain caliper with 0.2 mm accuracy. Percentiles were obtained with the LMS statistical method and were presented in tables divided in stages of 6 months and in curves graphics. The difference between Hispanic American and CDC mean values were provided for P3, P50 and P97 in mm and also were graphically represented. Results: skinfolds measurements obviously increased with age in both sexes but, in boys, this increase is much more marked in highest percentiles between 8 and 13 years; this maximum is reached earlier than what occurs in CDC reference. In both sexes, all percentiles analized in Hispanic American schoolchildren were higher than the CDC reference except P97 up to 10 or 13 years that was notably smaller. Conclusions: the skinfolds percentiles of Hispanic American children and adolescents differ from CDC that are usually used as reference. The values of subscapular and triceps skinfolds provided in this study, could be applied to populations of a similar ethnic background, especially in comparative studies of body composition (AU)

Introducción: la evaluación del grosor de los pliegues subcutáneos es una medida objetiva de la adiposidad. Es por tanto una herramienta útil para el diagnóstico nutricional y la prevención del riesgo metabólico asociado al exceso de grasa en la infancia y adolescencia. Objetivo: proporcionar valores percentilares de los pliegues adiposos subcutáneos subescapular y tricipital para escolares hispanoamericanos y compararlos con los valores publicados por los Centros para el Control y Prevención de Enfermedades (CDC) de los Estados Unidos, que comunmente se emplean como referencia en estos países. Métodos: se midió el pliegue subescapular y tricipital en 9.973 escolares entre 4 y 19 años procedentes de España, Argentina, Cuba, Venezuela y México con un calibre Holtain de 0,2 mm de precisión. Los percentiles fueron calculados mediante el método estadístico LMS y presentados en tablas divididas en intervalos de seis meses y en gráficos de curvas. La diferencia entre los valores medios hispanoamericanos y los valores del CDC se muestran para el P3, P50 y P97 en mm, y también gráficamente. Resultados: las medidas de los pliegues subcutáneos se incrementan obviamente con la edad pero, en niños, este incremento es mucho más marcado en los percentiles superiores entre los 8 y 13 años; este máximo es alcanzado antes que en la referencia del CDC. En ambos sexos, todos los percentiles analizados fueron superiores en los escolares hispanoamericanos, exceptuando el P97 por encima de los 10 o 13 años, donde resultó notablemente inferior. Conclusiones: los percentiles de pliegues adiposos de los niños y adolescentes hispanoamericanos difieren de la referencia del CDC. Los valores del pliegie subescapular y tricipital proporcionados en este estudio podrían ser aplicados en poblaciones de similar origen étnico, especialmente en estudios comparativos de la composición corporal (AU)

Geographical altitude, size, mass and body surface area in children (1-4 years) in the Province of Jujuy (Argentina).

BACKGROUND: Highland child populations show low growth rates. AIM: To evaluate the variation of size, mass and body surface area of Jujenean infants (1-4 years) as a function of geographic altitude. SUBJECTS AND METHODS: Nutritional status of 8059 healthy infants was determined based on weight and height data; body mass index, ponderal index, body surface area, body surface area/mass and ectomorphy were calculated. Variables were standardized with a provincial mean and WHO references. Data were grouped by age, sex and geographic altitude: Highlands (≥2500 masl) and Lowlands (<2500 masl). Chi-square, correlation and t-tests were applied. RESULTS: Highlands infants had higher prevalence of stunting, reduced height, weight, body surface area and ectomorphy; also higher body mass index, ponderal index and body surface area/mass. The population average z-score for height, weight and body surface area was positive in Lowlands and negative in Highlands. The opposite happened with body mass index, ponderal index and body surface area/mass. In Highlands and Lowlands the average z-score reference was negative for weight and height and positive for body mass index. Correlations between indices were high and significant, higher in Highlands. CONCLUSION: Jujenean children differ in size, mass and body surface area based on the geographical altitude and adverse nutritional and socioeconomic factors.

Prevalencia de sobrepeso y obesidad en escolares jujeños de diferente nivel altitudinal según las referencias IOTF, CDC y OMS / Prevalence of overweight and obesity in students from different altitudinal zones of Jujuy according to three intvernational references (IOTF, CDC and WHO)

Introducción. Se comparan las prevalencias de sobrepeso (SP) y obesidad (OB) en escolares jujeños de distintos niveles altitudinales utilizando las referencias de la International Obesity Task Force (IOTF), de los Centers for Disease Control (CDC) y de la Organización Mundial de la Salud (OMS), y la concordancia entre ellas. Materiales y métodos. Los datos de peso y talla de 15 541 escolares (PROSANE) se agruparon en tierras altas (TA) (= 2500 msnm) y bajas (TB) (< 2500 msnm), y en dos grupos de edad (5 a 6,99 y 11 a 12,99 años). Se calcularon las prevalencias de SP, OB y SP+OB según las referencias. Las diferencias entre variables y prevalencias se establecieron con la prueba de la ?² y la prueba de la t, y la concordancia entre criterios, con el índice kappa. Resultados. Los escolares de las TA presentaron menor peso, talla e índice de masa corporal (IMC) (p< 0,05). Las prevalencias de SP, OB y SP+OB con OMS fueron superiores, excepto para SP en ambos sexos de 11 a 12,99 años de TB y TA. Independientemente de las referencias, el sexo y la edad, las prevalencias de SP, OB y SP+OB fueron, en general, mayores en las TB. La concordancia entre las referencias IOTF/CDC fue buena-muy buena, y entre estas y las de la OMS, regular-moderada. Conclusiones. Los escolares de TA presentaron menor prevalencia de SB y OB. La mejor concordancia se dio entre las referencias IOTF y CDC.

Introduction. Prevalences of overweight and obesity in students from different altitudinal zones of Jujuy are compared using the International Obesity Task Force (IOTF), the Centers for Disease Control (CDC) and the World Health Organization (WHO) references, and the agreement among them. Material and Methods. Weight and height data from 15 541 students were grouped in highlands (HL) (=2500 MASL) and lowlands (LL) (<2500 MASL) and in two age groups (5-6.99 years old and 11-12.99 years old). Overweight and obesity prevalences were calculated according to the different references. The differences in outcome measures and prevalences were established using the ?2 test and the t test, and agreement among the criteria was calculated using the kappa index. Results. Students from the HL had lower weight, height and body mass index (BMI) values (p< 0.05). Overweight and obesity prevalences compared to the WHO reference were higher, except for overweight in students of both sexes, from 11 to 12.99 years old, from the HL and the LL. Regardless of the references, gender and age, overweight and obesity prevalences were generally higher in the LL. Agreement between the IOTF and the CDC was good-very good, and agreement among them and the WHO was fair-moderate. Conclusions. Students from the HL had a lower overweight and obesity prevalence. The greatest agreement was observed between the IOTF and the CDC references.

Prevalencia de sobrepeso y obesidad en escolares jujeños de diferente nivel altitudinal según las referencias IOTF, CDC y OMS / Prevalence of overweight and obesity in students from different altitudinal zones of Jujuy according to three intvernational references (IOTF, CDC and WHO)

Introducción. Se comparan las prevalencias de sobrepeso (SP) y obesidad (OB) en escolares jujeños de distintos niveles altitudinales utilizando las referencias de la International Obesity Task Force (IOTF), de los Centers for Disease Control (CDC) y de la Organización Mundial de la Salud (OMS), y la concordancia entre ellas. Materiales y métodos. Los datos de peso y talla de 15 541 escolares (PROSANE) se agruparon en tierras altas (TA) (= 2500 msnm) y bajas (TB) (< 2500 msnm), y en dos grupos de edad (5 a 6,99 y 11 a 12,99 años). Se calcularon las prevalencias de SP, OB y SP+OB según las referencias. Las diferencias entre variables y prevalencias se establecieron con la prueba de la ?² y la prueba de la t, y la concordancia entre criterios, con el índice kappa. Resultados. Los escolares de las TA presentaron menor peso, talla e índice de masa corporal (IMC) (p< 0,05). Las prevalencias de SP, OB y SP+OB con OMS fueron superiores, excepto para SP en ambos sexos de 11 a 12,99 años de TB y TA. Independientemente de las referencias, el sexo y la edad, las prevalencias de SP, OB y SP+OB fueron, en general, mayores en las TB. La concordancia entre las referencias IOTF/CDC fue buena-muy buena, y entre estas y las de la OMS, regular-moderada. Conclusiones. Los escolares de TA presentaron menor prevalencia de SB y OB. La mejor concordancia se dio entre las referencias IOTF y CDC.(AU)

Introduction. Prevalences of overweight and obesity in students from different altitudinal zones of Jujuy are compared using the International Obesity Task Force (IOTF), the Centers for Disease Control (CDC) and the World Health Organization (WHO) references, and the agreement among them. Material and Methods. Weight and height data from 15 541 students were grouped in highlands (HL) (=2500 MASL) and lowlands (LL) (<2500 MASL) and in two age groups (5-6.99 years old and 11-12.99 years old). Overweight and obesity prevalences were calculated according to the different references. The differences in outcome measures and prevalences were established using the ?2 test and the t test, and agreement among the criteria was calculated using the kappa index. Results. Students from the HL had lower weight, height and body mass index (BMI) values (p< 0.05). Overweight and obesity prevalences compared to the WHO reference were higher, except for overweight in students of both sexes, from 11 to 12.99 years old, from the HL and the LL. Regardless of the references, gender and age, overweight and obesity prevalences were generally higher in the LL. Agreement between the IOTF and the CDC was good-very good, and agreement among them and the WHO was fair-moderate. Conclusions. Students from the HL had a lower overweight and obesity prevalence. The greatest agreement was observed between the IOTF and the CDC references.(AU)

Variabilidad interpoblacional y diferencias ambientales, maternas y perinatales del peso al nacimiento / Interpopulation variability and environmental, maternal and perinatal differences from the weight to the birth

Las poblaciones humanas difieren entre sí respecto a las variables auxológicas, incluyendo el peso al nacimiento. Estas diferencias obedecen a un vasto conjunto de factores genéticos y ambientales. Las distintas categorías que se deducen a partir del peso al nacimiento (bajo peso al nacimiento, muy bajo peso al nacimiento, etc.) son utilizadas corrientemente para evaluar la salud y nutrición de distintos grupos sociales, étnicos o geográficos, productos de las sociedades actuales. Dado que la compresión de los factores que contribuyen a la variabilidad del peso al nacimiento resulta esencial para interpretar correctamente estos diagnósticos socio sanitarios, en este trabajo se analizan las principales diferencias ambientales, maternas y perinatales que influyen sobre el peso al nacimiento.

Variabilidad interpoblacional y diferencias ambientales, maternas y perinatales del peso al nacimiento / Interpopulation variability and environmental, maternal and perinatal differences from the weight to the birth

Las poblaciones humanas difieren entre sí respecto a las variables auxológicas, incluyendo el peso al nacimiento. Estas diferencias obedecen a un vasto conjunto de factores genéticos y ambientales. Las distintas categorías que se deducen a partir del peso al nacimiento (bajo peso al nacimiento, muy bajo peso al nacimiento, etc.) son utilizadas corrientemente para evaluar la salud y nutrición de distintos grupos sociales, étnicos o geográficos, productos de las sociedades actuales. Dado que la compresión de los factores que contribuyen a la variabilidad del peso al nacimiento resulta esencial para interpretar correctamente estos diagnósticos socio sanitarios, en este trabajo se analizan las principales diferencias ambientales, maternas y perinatales que influyen sobre el peso al nacimiento.(AU)