Factors associated with birth weight and birth length among term newborns in Vietnam: a retrospective cross-sectional study

Abstract

PURPOSE: Birth weight and birth length are essential indicators of neonatal health and later development. However, evidence from Vietnam on the multidimensional determinants of these outcomes remains limited. Guided by the biopsychosocial model, this study examined factors associated with birth weight and birth length among term newborns. METHODS: This retrospective cross-sectional study included 198 term singleton live births at Hai Phong Hospital of Obstetrics and Gynecology, Vietnam. Data were extracted from the medical records of newborns born at the hospital between December 2023 and May 2024. Because the variables did not meet parametric assumptions, the Mann-Whitney U test, Kruskal-Wallis H test, and Spearman correlation coefficient were used as nonparametric alternatives to the independent-samples t-test, analysis of variance, and Pearson correlation coefficient, respectively. Two multiple linear regression models were constructed to identify independent predictors of birth weight and birth length, with statistical significance set at p<.05. RESULTS: In the multivariable analysis, gestational age (β=.37, p<.001), maternal pre-pregnancy weight (β=.24, p<.001), protein supplementation (β=.13, p=.040), and infant sex (β=-.16, p=.008) were significant predictors of birth weight. Paternal height (β=.47, p<.001), gestational age (β=.23, p<.001), maternal height (β=.22, p<.001), and maternal pre-pregnancy weight (β=.16, p=.009) were significant predictors of birth length. CONCLUSION: Within the biopsychosocial framework, interrelated biological and behavioral factors were associated with birth weight and birth length among term newborns. Prenatal assessment of maternal and paternal characteristics may help inform strategies to support fetal growth, particularly in resource-limited settings.