Prevalencias de bajo peso y pequeño para la edad gestacional en Argentina: comparación entre el estándar INTERGROWTH-21st y una referencia argentina / Prevalence of low weight and small for gestational age in Argentina: Comparison between the INTERGROWTH-21st standard and an Argentine reference

Introducción. Bajo peso al nacer (< 2500 g) incluye recién nacidos pretérmino y a término pequeños para la edad gestacional (PEG) (< P10). La Organización Mundial de la Salud define bajo peso (BP) como peso al nacer < P3 peso/edad. Internacionalmente, no existe consenso sobre estándares y/o referencias de peso al nacer por edad gestacional (EG) para evaluar PEG y BP en pretérminos. Se determinó la prevalencia de BP y PEG con el estándar INTERGROWTH-21st y la referencia poblacional argentina de Urquía, y se analizó la concordancia de las prevalencias entre ambas herramientas. Población y métodos. Estudio observacional, analítico y retrospectivo realizado sobre los nacimientos registrados en 2013 en el Ministerio de Salud de la Nación. Los criterios de exclusión fueron EG < 24+0 -> 42+6 semanas, embarazo gemelar y ausencia de datos de peso, EG y sexo. Se calcularon las prevalencias por sexo, regiones y categorías de prematurez de BP y PEG con el estándar y la referencia. La concordancia se evaluó con Kappa. Resultados. Las prevalencias de BP y PEG fueron más altas con el estándar en pretérmino; lo contrario se observó en recién nacidos a término. La significación estadística varió según categorías de EG, sexo y regiones. Las prevalencias más altas se presentaron en regiones del norte argentino y las concordancias entre prevalencias oscilaron entre débiles y muy buenas. Conclusiones. Las concordancias de prevalencias de BP y PEG obtenidas con el estándar y la referencia en pretérmino y a término fueron moderadas, y se observó variabilidad interregional. Los resultados plantean nuevas perspectivas auxológicas en la evaluación epidemiológica del retardo del crecimiento intrauterino en Argentina.

Introduction. The term "low birth weight" (< 2500 g) encompasses preterm newborns and term newborns small for gestational age (SGA) (< P10). The World Health Organization defines low weight (LW) as a birth weight < P3 of weight/age. There is no consensus at an international level about which standards and/or references related to birth weight for gestational age (GA) should be used to assess SGA and LW among preterm newborns. LW and SGA prevalence was determined using the INTERGROWTH-21st standard and Urquia's reference for the Argentine population, and agreement between the prevalence observed with both tools was analyzed. Population and methods. Observational, analytical, and retrospective study based on all births occurred in 2013 as reported by the Argentine National Ministry of Health. Exclusion criteria were GA < 24+0 - > 42+6 weeks, twin pregnancy, and missing data on weight, GA, and sex. Prevalence was estimated by sex, region, and prematurity category for LW and SGA according to the standard and the reference. Agreement was assessed using the Kappa index. Results. The prevalence of LW and SGA was higher according to the standard among preterm newborns; the contrary was observed among full-term newborns. Statistical significance varied based on GA category, sex, and region. A higher prevalence was observed in the northern regions of Argentina, and agreement among prevalence values ranged from weak to very good. Conclusions. Prevalence agreement of LW and SGA observed according to the standard and the reference among preterm and full-term newborn infants was moderate, with interregional variability. Results propose new auxological perspectives in the epidemiological assessment of intrauterine growth restriction in Argentina.

Birth weight classification in gestational diabetes: is there an ideal chart?

Introduction: Gestational diabetes mellitus (GDM) is associated to increased rates of large for gestational age (LGA) newborns and macrosomia. Several charts are used to classify birth weight. Is there an ideal chart to classify newborns of GDM mothers? Methods: We evaluated adequacy of birth weight of 332 neonates born to GDM mothers at Hospital de Clínicas de Porto Alegre, Brazil. Newborns were classified according to gestational age as small (SGA), adequate, or large (LGA) based on four charts: Alexander, Pedreira, INTERGROWTH 21st Project, and SINASC-2012. The latter was built using data from a large national registry of 2012, the Born Alive National Surveillance System (Sistema de Informações de Nascidos Vivos ­ SINASC), which included 2,905.789 birth certificates. Frequencies of SGA and LGA and Kappa agreement were calculated. Results: In non-gender adjusted curves, SGA rates (95% confidence interval) varied from 8% (5-11) to 9% (6-13); LGA rates, from 11% (8-15) to 17% (13-21). For males, SGA rates varied from 3% (1-6%) to 6% (3-11%), and LGA rates, from 18% (13-24%) to 31% (24-38%); for females, SGA rates were from 3% (1-7%) to 10% (6-16%) and LGA rates, from 11% (6-16%) to 19% (13-26%). Kappa results were: ALEXANDER vs. SINASC-2012: 0.80 (0.73-0.88); INTERGROWTH 21st vs. SINASC-2012 (adjusted by sex): 0.62 (0.53-0.71); INTERGROWTH 21st vs. PEDREIRA: 0.71 (0.62-0.79); SINASC-2012 (by sex) vs. PEDREIRA: 0.86 (0.79-0.93). Conclusions: Misclassification has to be taken into account when evaluating newborns of GDM mothers, as LGA rates can almost double depending on the chart used to classify birth weight (AU)