The Impact of Timing of Introduction of Solids on Infant Body Mass Index

J Pediatr. 2016 Dec;179:104-110.e1. doi: 10.1016/j.jpeds.2016.08.064. Epub 2016 Sep 20.


Objectives: To evaluate the associations between breastfeeding duration, age at solids introduction, and their interaction in relation to infant (age 9-15 months) above normal body mass index (BMI).

Study design: Cross-sectional, population-based study with 3153 infants from Melbourne (2007-2011). Above normal BMI (z score > 2, equivalent to >97.7th percentile) defined using the World Health Organization standard.

Results: Both longer duration of full and any (full or partial) breastfeeding were associated with lower odds of above normal BMI (eg, aOR, 0.37 [95% CI, 0.22-0.60] for full breastfeeding 4-5 months versus 0-1 months). Compared with introduction of solids at 5-6 months, both early and delayed introduction were associated with increased odds of above normal BMI (aOR for 4 months, 1.75 [95% CI, 1.10-2.80] and for ≥7 months, 2.64 [95% CI, 1.26-5.54] versus 6 months). Such associations differ by breastfeeding status at 4 months (interaction P = .08). Early introduction of solids was associated with increased odds of above normal BMI in both infants fully or partially breastfed for ≥4 months (aOR, 3.66; 95% CI, 1.41-9.51) and those breastfed for <4 months (aOR, 3.11; 95% CI, 1.39-6.97). Introduction of solids at ≥7 months was associated with increased odds of above normal BMI (aOR, 5.79; 95% CI, 1.91-17.49) among infants breastfed for <4 months only.

Conclusion: Introduction of solids at 5-6 months, compared with either early or delayed introduction, is associated with decreased odds of above normal BMI at 1 year of age, regardless of infants' breastfeeding status at 4 months. These results may have implications for public health guidelines with regard to recommendations about the optimal timing of the introduction of solid foods in infancy.

Keywords: childhood obesity; childhood overweight; early life nutrition; infant; population-based studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Body Mass Index*
  • Breast Feeding*
  • Cross-Sectional Studies
  • Feeding Methods
  • Female
  • Food
  • Humans
  • Infant
  • Male
  • Time Factors