Effects of Infant Formula Type on Early Childhood Growth Outcomes: A Retrospective Cohort Study

TL;DR

This study found that non-standard infant formulas may lead to higher weight and BMI in early childhood compared to standard formulas and breastfeeding.

Contribution

The study provides new evidence on the differential growth effects of non-standard infant formulas in early childhood.

Findings

Infants on non-standard formulas had higher weight-for-age and BMI z-scores at 12 months compared to standard formula-fed infants.

At 24 months, only weight-for-age z-scores remained significantly higher for non-standard formula users.

Both non-standard and standard formula-fed infants had higher growth z-scores than breastfed infants at 12 and 24 months.

Abstract

Objective: This study examines the effects of non-standard (lactose-reduced, hydrolyzed), cow-milk-based infant formulas on early childhood growth outcomes compared to standard formulas and breastfeeding. Methods: This retrospective cohort study included full-term infants with a birth weight >2500 g. Exposure and control data, including the type of infant formula [non-standard vs. standard] and breastfeeding status, were obtained at 2-month well visits. Growth outcomes (weight-for-age, length-for-age, BMI (Body Mass Index), and weight-for-length z-scores] were calculated using WHO (World Health Organization) growth standards at 1- and 2-year well visits. Generalized linear mixed models were used to evaluate associations between formula type and growth outcomes, adjusting for maternal, infant, and socioeconomic factors. Results: A total of 5515 infants were included in the final analysis. Feeding practices included exclusive breastfeeding (35%), standard formula (42%), and non-standard formula (23%). Infants fed non-standard formulas had significantly higher weight-for-age, BMI, and weight-for-length z-scores at 12 months than those fed standard formulas, and after controlling for other covariates, weight-for-age and BMI z-scores remained significantly higher in the non-standard formula infants. At 24 months, only weight-for-age z-scores remained significantly higher for non-standard formula users compared to standard formula users. Both non-standard and standard formula groups showed significantly higher weight-for-age, BMI, weight-for-length, and length-for-age z-scores compared to breastfed infants at 12 and 24 months. Conclusions: Non-standard infant formula may have a differential effect on growth during the first year of life compared to standard infant formula and breastfeeding. Future research should explore the long-term health effects of non-standard infant formula use and the risk of obesity.

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