Fetal growth does not modify the relationship of infant weight gain with childhood adiposity and blood pressure in the Southampton women’s survey

Background: Rapid infant weight gain is a risk factor for childhood obesity. This relationship may depend on whether infant weight gain is preceded by in-utero growth restriction. Aim: Examine whether fetal growth modifies the relationship between infant weight gain and childhood adiposity and blood pressure. Subjects and methods: 786 children in the Southampton Women’s Survey. We related infant weight gain (weight at 2 years-birth weight) to body mass index (BMI), %body fat, trunk fat (kg), systolic (SBP) and diastolic blood pressure (DBP) at age 6–7 years. Mean estimated fetal weight (EFW) between 19–34 weeks and change in EFW (19–34 weeks) were added to models as effect modifiers. Results: Infant weight gain was positively associated with all childhood outcomes. We found no evidence that these effects were modified by fetal growth (p > .1 for all interaction terms). For example, a 1 standard deviation (SD) increase in infant weight gain was associated with an increase in BMI z-score of 0.51 (95% CI 0.37;0.64) when EFW-change was set at -2 SD-scores compared with an increase of 0.41 (95% CI 0.27;0.54, p((interaction))=.48) when set at 2 SD-scores. Conclusion: The documented adverse consequences of rapid infant weight gain may occur regardless of whether growth was constrained in-utero.