Effect of predominant breastfeeding duration on infant growth: a prospective study using nonlinear mixed effect models

Abstract

ResumoObjetivo: Avaliar o efeito da duração da amamentação predominante no crescimento infantil com uso de modelos para medidas repetidas.Métodos: Trata-se de estudo prospectivo com quatro ondas de seguimento realizadas com aproximadamente 0,5, 2, 6 e 9 meses pós-parto, que incluiu entrevistas estruturadas e coleta de dados de peso, comprimento e sobre práticas de aleitamento. O estudo foi desenvolvido em um Centro Municipal de Saúde no Rio de Janeiro, Brasil, entre 1999 e 2001. Quatrocentos e setenta e nove mulheres e seus filhos foram estudados. As variáveis dependentes foram o peso e o comprimento, aferidas em cinco momentos (ao nascimento, 0,5, 2, 6 e 9 meses). O crescimento foi analisado usando modelos não lineares de efeitos mistos. Resultados:Crianças com maior duração de aleitamento predominante apresentaram maior velocidade de crescimento durante os primeiros meses de vida, mas alcançaram peso e comprimento de equilíbrio menor quando comparadas com crianças que receberam outros leites não humanos no início da vida. A idade na qual a velocidade de crescimento de crianças alimentadas com fórmulas tornou-se maior do que as amamentadas foi de 6,75 meses para meninos e 7 meses para meninas. Conclusões:Esse estudo confirma a presença de diferenças no crescimento físico segundo práticas de aleitamento a partir dos 6 meses de vida. O uso de modelos não lineares permitiu maior precisão na estimativa dos parâmetros. Acredita-se que essa abordagem facilite a análise e interpretação de dados de crescimento nos níveis individual e populacional.J Pediatr (Rio J). 2008;84(3):237-243: Amamentação, crescimento infantil, modelos mistos não lineares, medidas repetidas. AbstractObjective: The aim of this study is to assess the effect of predominant breastfeeding duration on infant growth by means of repeated measurements model. Methods:This prospective study is comprised of four follow-up evaluations at approximately 0.5, 2, 6 and 9 months after birth, including structured interviews that simultaneously gathered information regarding infant growth and breastfeeding practices. The study took place in a healthcare center in Rio de Janeiro, Brazil, from 1999 to 2001. Four hundred seventy-nine postpartum women and their newborns were enrolled in the cohort. Body weight and length measurements taken at five different occasions (birth, 0.5, 2, 6, and 9 months) constituted the dependent variables. We expressed the growth process using nonlinear mixed models. Results:Infants with longer predominant breastfeeding duration, although growing faster in the first months of life, reached an inferior equilibrium body weight and length compared to infants who received nonhuman milk earlier in life. The age at which the rate of weight gain of the formula-fed infants becomes greater than that of the breastfed infants is approximately 6.75 months for boys and 7 months for girls. Conclusions:This study confirms the differences observed in infant growth according to different breastfeeding practices starting from the sixth month of life. Use o...

Determinantes da velocidade média de crescimento de crianças até seis meses de vida: um estudo de coorte

“…Contrary to our results, Spyrides et al 8 observed that children born with cesarean delivery tended to have greater weight gain rates than those born vaginally. These authors point out that literature has investigated the relation between cesarean deliveries with breastfeeding, but the influence of this type of delivery on growth in the first months of the infant's life is not known.…”

“…Augusto e Souza et al 13 , studying 347 children, observed a higher rate of daily weight gain in boys during the first quarter. In the study by Spyrides et al 8 with children up to nine months of age, lower weight and size gain rates were also observed among girls. A study 4 that analyzed data from 181 children on exclusive breastfeeding (EBF) up to the sixth month of age found that boys' weight gain was higher only in the first quarter.…”

“…The study by Mihrshahi et al 17 observed that male gender was a non-modifiable factor for rapid weight gain among children. Boys tend to have a higher birth weight and a faster weight gain rate 8 . A discussion is presented by Jaldin et al 4 , which is based on other studies and justifies this difference between genders by anatomical and physiological characteristics, where boys have larger body structures and muscle tissue and girls have lower birth weight.…”

“…These measures performed repeatedly in a given period provide better consistency in the assessment of the growth period 8 . The growth rate corresponds to increased weight, size or other anthropometric parameter in a given time interval (days or months, for example), representing the current growth dynamics.…”

“…However, few studies have proposed to evaluate the rate of weight and size growth, as well as its determinants 9 . Some Brazilian studies 3,4,8,12,13 have investigated the relationship between breastfeeding (BF) and child growth. Studies that evaluate infant growth rate according to the variables analyzed in this study are not common in Brazilian literature, whose objective is to investigate some factors that contributed to a higher or lower growth rate of infants up to the sixth month of life.…”