Key messages

A new study highlights the importance of encouraging and supporting extended breastfeeding for childhood obesity prevention.  Using longitudinal data from an obesity prevention program in pregnancy/early infancy, the study showed that infants who were breastfed from birth to 12 months had lower weight status (BMI z-score) at 12-60 months compared to infants who were mixed (breastmilk and formula) or formula fed.  Breastfeeding duration for 6 months or more, compared to less than 6 months, were also associated with healthier growth pattern.  Timing of solid foods introduction was not associated with weight/growth pattern.

What is the issue?

Infant feeding guidelines internationally recommend infants to be fed exclusively with breast milk in the first six months of life and continued breastfeeding to two years of age.  Australian National Health Survey data from 2017-18 showed that only 29% of infants were exclusively breastfed to six months, and 41% received breastmilk for at least 12 months.  There is good evidence that breastfeeding is associated with numerous short- and long-term benefits including healthier growth pattern and weight status in early childhood.  The evidence on the benefits of breastfeeding in preventing obesity development is clear when compared to formula feeding.   But what if parents combine feeding modes (both breastmilk and formula)?  Would they be similarly protected?   Studies that have addressed this question have used different analysis approaches, making comparison between studies difficult.

What did we do?

Using data from the Healthy Beginnings Trial, we examined for any relationships between infant feeding mode, breastfeeding duration, and timing of solid food introduction with growth pattern of standardised body mass index (BMI z-score).  The analysis considered growth pattern from birth to 5 years given how infants were fed during infancy.  Two commonly used analysis methods were compared to test if the different approaches could influence the results.  Healthy Beginnings Trial is an Australian early family-focused intervention addressing the prevention of overweight and obesity in early childhood.

What did we find?

Both analysis approaches produced similar findings.  Children who were predominantly breastfed from birth to 12 months showed healthier growth pattern (lower BMI z-score) until age five than formula-fed or mixed-fed children.  Healthier growth pattern was also shown with longer breastfeeding duration for 6 months or longer compared to less than 6 months.  In contrast to milk feeding methods, the timing of solid foods introduction did not predict growth pattern.

What does it mean?

This study provides robust evidence supporting infant feeding guidelines and public health policies to encourage and support any and extended breastfeeding for childhood obesity prevention.  The findings were consistent regardless of the different analysis approaches thus providing greater confidence on the strength of the evidence.

This is the first study detailing the use of two distinct longitudinal data analysis methods to evaluate the association between infant feeding and BMI z-score trajectories in early childhood.  The application of the two longitudinal data analysis approaches might be valuable for nutrition and public health researchers when selecting a method of analysis.

Read the full paper here

https://www.nature.com/articles/s41366-021-00892-5?proof=t%3B

For further details, contact Jazzmin Zheng j.zheng@deakin.edu.au