Antenatal and early infant predictors of postnatal growth in rural Vietnam: a prospective cohort study

Objective To determine which antenatal and early-lifefactors were associated with infant postnatal growth in aresource-poor setting in Vietnam. Study design Prospective longitudinal study followinginfants (n=1046) born to women who had previouslyparticipated in a cluster randomised trial of micronutrientsupplementation (ANZCTR:12610000944033), Ha Nam province, Vietnam. Antenatal and early infant factorswere assessed for association with the primary outcomeof infant length-for-age z scores at 6 months of age usingmultivariable linear regression and structural equationmodelling.Results Mean length-for-age z score was -0.58(SD 0.94) and stunting prevalence was 6.4 . Usingstructural equation modelling, we highlighted the role ofinfant birth weight as a predictor of infant growth in thefirst 6 months of life and demonstrated that maternalbody mass index (estimated coefficient of 45.6 g/kg/m2;95 CI 34.2 to 57.1), weight gain during pregnancy(21.4 g/kg; 95 CI 12.6 to 30.1) and maternal ferritinconcentration at 32 weeks? gestation (-41.5 g pertwofold increase in ferritin; 95 CI -78 to -5.0) wereindirectly associated with infant length-for-age z scores at6 months of age via birth weight. A direct associationbetween 25-(OH) vitamin D concentration in latepregnancy and infant length-for-age z scores (estimatedcoefficient of -0.06 per 20 nmol/L; 95 CI -0.11 to-0.01) was observed.Conclusions Maternal nutritional status is an importantpredictor of early infant growth. Elevated antenatal ferritinlevels were associated with suboptimal infant growth inthis setting, suggesting caution with iron supplementationin populations with low rates of iron deficiency.