How changes in weight from birth to early adulthood affect lung development

A new study has looked at how weight affects the way the lungs work over time. Problems with the development of the lungs in childhood can affect how well they work in adulthood. One of the things that can affect lung development is a child’s weight; being overweight or underweight can cause the lungs to work less well as a person grows up.

What did the study look at?

The authors of this study used the height and weight measurements of over 3,000 children recorded many times between 6 months and 24 years old. They calculated a person’s body mass index (BMI), which uses height and weight to look at whether a person is a healthy weight for their height. They grouped these measurements into patterns, or “trajectories” and compared these to measurements looking at how well the lungs were working from 8 years old to 24 years old.

What do the results show?

The authors divided people into six different trajectories:

1. BMI was normal at an early age but lower than normal at later dates

2. BMI was low at an early age, increased in childhood but then dropped back to normal in the teenage years (adolescence)

3. BMI was normal throughout the study

4. BMI was normal at an early age but higher than normal at later dates

5. BMI was normal at an early age, high in childhood and kept increasing in adolescence

6. BMI was high at an early age and during childhood, and kept increasing in adolescence

The authors used these trajectories to spot patterns in how BMI affects the way the lungs worked. Their findings included:

• Groups whose BMI increased in childhood had bigger lung capacity but showed signs of some restriction in the airways, which can stop the lungs from fully expanding when a person breathes in. If the BMI kept increasing in the teenage years, lung development slowed down and they had worse lung function at 24 years old.
• In groups where the BMI returned to normal after being high, lung function problems resolved by 24 years old.
• Children with a low BMI throughout childhood had slower lung development and smaller lung sizes.

Why is this important?

Lung development in children can be flexible, both speeding up and slowing down. A high BMI during childhood and adolescence can result in poorer lung function as an adult. But these problems can be reversed if the BMI is brought back to normal. A low BMI is also linked to poorer lung development. Interventions that aim to keep a healthy BMI throughout childhood could improve lung health later in life.

Read the original research paper.