Chest circumference in full-term newborns: how can it be predicted?

BACKGROUND: Although over the years a number of studies have used chest circumference (CC) as a sensitive tool to identify the health status of infants, a particularly important aspect for this population is the lack of data on normal values and prediction equations. In order to facilitate and validate the interpretation of CC data in newborn (NB), the aim was to study the relation between CC and other anthropometric variables and develop a predictive equation for CC in a population of full-term newborns. METHODS: Cross-sectional study, carried out with full-term infants. The anthropometric (CC, head circumference - HC, length, age and weight) and hemodynamic variables were evaluated during the first 24 h of life. Bivariate analysis was performed between CC and HC, weight, length and type of delivery, followed by multiple linear regression analysis, including variables that were significant in the bivariate analysis. For data analysis, we used the SPSS program, considering p < 0.05 and 95% CI. RESULTS: The birth weight of the 120 NB varied between 2580 and 4225 g (mean 3360 g) and the gestational age between 37 and 42 weeks (mean 39 weeks). Approximately 61% of the sample were delivered vaginally and 67 (56%) were boys. The variables that remained statistically associated with CC after multivariate analysis were weight (ß 0.003, CI: 0.002: 0.003, p = 0.001) and HC (ß 0.287, CI: 0.156: 0.417, p = 0.001). For the linear regression model, the predictive equation of CC was 14.87+ (0.003 x weight) + (0.287 x HC), with a prediction of 76%. CONCLUSION: The results show a positive correlation between CC and weight, length and HC, and based on the linear regression model, the predictive equation for CC is based only on weight and HC.

Medidas repetidas no estudo de características de crescimento e carcaça avaliadas por ultrassom em novilhas de corte cruzadas / Repeated measures in the study of growth and ultrasound carcass traits in cross heifers

Com o objetivo de estudar o desenvolvimento de características de carcaça obtidas por ultrassom, peso vivo, perímetro torácico e altura do posterior, dados longitudinais foram analisados por diferentes estruturas de (co)variâncias residuais que consideram homogeneidade ou heterogeneidade de (co)variâncias, para melhor representar a variabilidade entre observações e dentro de indivíduo, ao longo do tempo. As medidas foram obtidas em 120 novilhas, sendo 60 ½ Braunvieh x » Santa Gertrudes » x Nelore e 60 ½ Santa Gertrudes x ½ Nelore. As características foram avaliadas em intervalos de 28 dias, totalizando até cinco medidas em cada grupo. Foram comparados diversos modelos com o intuito de identificar estruturas de (co)variâncias residuais adequadas para melhor representar a variação das medidas dentro de indivíduos, com base no critério Schwarzs Bayesian Criterion. Posteriormente, avaliou-se o modelo mais adequado para regredir as características em função da idade, usando polinômios ordinários e verificando a necessidade de diferentes curvas para cada grupo genético. Diferentes estruturas de (co)variância residual devem ser consideradas em análise de dados longitunais, visando melhor representar a variabilidade entre observações e dentro de indivíduo. Os grupos genéticos estudados diferem entre si, ao longo do tempo, para as características peso, altura do posterior, perímetro torácico e área de olho de lombo.(AU)`ipt

The aim of this paper was to study the development of carcass traits obtained by ultrasound, weight, chest circumference and hip height by longitudinal data of two genetic groups of heifers. These data were analyzed by different structures of residual (co)variance consider homogeneity or heterogeneity of (co)variances to better represent the variability between and within individual observations over the time. The traits were obtained in 60 animals ½ Braunvieh x » Santa Gertrudes x » Nelore and 60 animals ½ Santa Gertrudes x ½ Nelore. The traits were evaluated at intervals of 28 days. The comparison was done with several models, based on the criterion SBC (Schwarzs Bayesian Criterion) with the goal of identifying structures of residual (co) variance more appropriate to best represent the variation of the measures within individuals. Later, as the animals were measured at different ages, it was evaluated the most appropriate model to regress these traits as a function of age, using ordinary polynomials and verifying the need for different curves for each genetic group. The results indicated that it should consider different structures of residual (co)variance to better represent the variability between and within individual observations. For weight, hip height, chest circumference and longissimus muscle area traits there are differences in the genetic group over the time.(AU)

Medidas repetidas no estudo de características de crescimento e carcaça avaliadas por ultrassom em novilhas de corte cruzadas / Repeated measures in the study of growth and ultrasound carcass traits in cross heifers

Com o objetivo de estudar o desenvolvimento de características de carcaça obtidas por ultrassom, peso vivo, perímetro torácico e altura do posterior, dados longitudinais foram analisados por diferentes estruturas de (co)variâncias residuais que consideram homogeneidade ou heterogeneidade de (co)variâncias, para melhor representar a variabilidade entre observações e dentro de indivíduo, ao longo do tempo. As medidas foram obtidas em 120 novilhas, sendo 60 ½ Braunvieh x » Santa Gertrudes » x Nelore e 60 ½ Santa Gertrudes x ½ Nelore. As características foram avaliadas em intervalos de 28 dias, totalizando até cinco medidas em cada grupo. Foram comparados diversos modelos com o intuito de identificar estruturas de (co)variâncias residuais adequadas para melhor representar a variação das medidas dentro de indivíduos, com base no critério Schwarz’s Bayesian Criterion. Posteriormente, avaliou-se o modelo mais adequado para regredir as características em função da idade, usando polinômios ordinários e verificando a necessidade de diferentes curvas para cada grupo genético. Diferentes estruturas de (co)variância residual devem ser consideradas em análise de dados longitunais, visando melhor representar a variabilidade entre observações e dentro de indivíduo. Os grupos genéticos estudados diferem entre si, ao longo do tempo, para as características peso, altura do posterior, perímetro torácico e área de olho de lombo.`ipt

The aim of this paper was to study the development of carcass traits obtained by ultrasound, weight, chest circumference and hip height by longitudinal data of two genetic groups of heifers. These data were analyzed by different structures of residual (co)variance consider homogeneity or heterogeneity of (co)variances to better represent the variability between and within individual observations over the time. The traits were obtained in 60 animals ½ Braunvieh x » Santa Gertrudes x » Nelore and 60 animals ½ Santa Gertrudes x ½ Nelore. The traits were evaluated at intervals of 28 days. The comparison was done with several models, based on the criterion SBC (Schwarz’s Bayesian Criterion) with the goal of identifying structures of residual (co) variance more appropriate to best represent the variation of the measures within individuals. Later, as the animals were measured at different ages, it was evaluated the most appropriate model to regress these traits as a function of age, using ordinary polynomials and verifying the need for different curves for each genetic group. The results indicated that it should consider different structures of residual (co)variance to better represent the variability between and within individual observations. For weight, hip height, chest circumference and longissimus muscle area traits there are differences in the genetic group over the time.