Body mass index trajectories during the first year of life and their determining factors

Area of Science:

• Pediatrics
• Public Health
• Growth and Development

Background:

• Childhood obesity is a growing concern with origins in early life.
• Understanding infant body mass index (BMI) trajectories is crucial for identifying at-risk populations.
• Early life factors significantly influence long-term health outcomes.

Purpose of the Study:

• To analyze the different patterns (trajectories) of body mass index (BMI) in infants during their first year of life.
• To identify the prenatal and early life factors that predict these distinct BMI trajectories.
• To inform targeted interventions for preventing unhealthy weight gain in infancy.

Main Methods:

• Utilized data from the Infant Feeding Practices Survey II, including 2320 children with multiple BMI measurements in the first year.
• Employed latent class growth analysis to define distinct infant BMI trajectories.
• Used multinomial logistic regression to assess the association between prenatal/early life factors and identified BMI trajectories.

Main Results:

• Identified three infant BMI trajectories: "low-stable" (81.6%), "high-stable" (15.6%), and "rising" (2.8%).
• Factors associated with higher BMI trajectories included being male, preterm birth, maternal overweight status, and maternal ethnicity (Hispanic, non-Hispanic Black).
• Maternal smoking during pregnancy increased the likelihood of high-stable BMI. Higher income and adherence to breastfeeding guidelines reduced the risk of a rising BMI trajectory.

Conclusions:

• Distinct infant body mass index (BMI) trajectories are observable within the first year of life.
• Identifying predictors of these trajectories highlights vulnerable groups and modifiable risk factors.
• Findings support the development of targeted prenatal and postnatal interventions to promote healthy infant growth and prevent obesity.