Childhood body mass index trajectory determines risk factors for adult cardiovascular disease

Health and Wellness 3. dec 2020 3 min Research group leader, PhD Jennifer Lyn Baker Written by Kristian Sjøgren

New Danish research shows that children with a growth trajectory towards overweight from ages 6 to 14 years are more likely to develop several risk factors for cardiovascular disease.

We are supposed to gain weight from the minute we are born.

Some children gain a little at a time; others accumulate more weight than expected as the years go by.

Plotting the trend in each child’s body mass index (BMI) shows that this increases over time for most children – a little for some and more for others.

New Danish research now shows that the people who experience the greatest increase in BMI during childhood are more likely to develop various risk factors for cardiovascular disease, including high blood pressure, high levels of triglycerides, diabetes or greater waist circumference.

This result is not surprising, but the study nevertheless addresses the question in a new way and identifies patterns that may help to improve understanding of how weight gain in childhood and adolescence affects adult health.

“This study is interesting because, for the first time, we are not examining BMI at a specific time in childhood and adolescence but instead looking at trends in BMI over several years. This provides a more holistic picture of childhood weight than just using a single time point,” explains a researcher behind the study, Jennifer Lyn Baker, Research Group Leader, Center for Clinical Research and Prevention, Frederiksberg Hospital.

The research has been published in Atherosclerosis.

Using Denmark’s unique health data on children

Jennifer Lyn Baker and colleagues used Denmark’s extensive health records that school nurses and doctors painstakingly collected for children born between 1930 and 1996 who attended schools in Copenhagen.

These records listed the weight and height of all the children annually during their school years.

The researchers could therefore determine the BMI trajectories for each child from starting school at 6 years until 14 years.

The researchers divided the individual trajectories into five groups that represent different BMI trajectories from low to high from 6 to 14 years old.

The averages for the groups from 6 to 14 years old were:

1. BMI from 14 to 16

2. BMI from 15 to 18

3. BMI from 16 to 19

4. BMI from 16 to 22

5. BMI from 18 to 25

A BMI of 25 is the cut-off between normal weight and overweight for adults. Data for 2,466 children were gathered.

“An interesting aspect is that these children are not classically overweight but represent a sample of relatively normal-weight children. In the past, studies have investigated the significance of being overweight or obese in childhood, but here we looked much more broadly at trends in childhood BMI,” explains Jennifer Lyn Baker.

High BMI increases the likelihood of having risk factors for adult cardiovascular disease

The researchers divided the children into groups based on their BMI trajectories and then identified the same children as adults in the internationally recognized Copenhagen City Heart Study, in which researchers monitored a population sample and mapped their health and lifestyle from 1976 to 2015.

The Copenhagen City Heart Study contains data on the participants’ BMI, waist circumference, serum cholesterol, blood pressure, triglycerides and much more.

The researchers compared the childhood BMI trajectories from the school nurses’ records with the probability of the same adults from the Copenhagen City Heart Study developing various risk factors for cardiovascular disease and identified the relevant factors for each childhood BMI trajectory group.

The results showed that the people with the largest increase in childhood BMI were most likely to have up to 11 risk factors for cardiovascular disease as adults.

The likelihood of having these risk factors decreased as the BMI trajectory decreased, such that the children with the lowest increase in BMI had the lowest probability of developing the risk factors later in life.

“We expected that children with a high BMI and BMI trajectory in childhood would have a higher risk of developing various risk factors for cardiovascular disease as adults, but we did not know which risk factors would be associated. We can see that now,” explains Jennifer Lyn Baker.

Minimizing risk by avoiding weight gain in adolescence or in adulthood

Very interestingly, the results also show that the BMI trajectory from age 14 years to adulthood is strongly associated with developing various risk factors for cardiovascular disease as an adult.

So the children with a high BMI at age 14 years did not necessarily have a high risk of developing these risk factors if they avoided gaining excess weight in adolescence or early adulthood.

“It is encouraging that your risk factors are not set in stone just because you have a high BMI and a high BMI trajectory as a child. This can be changed. However, for the vast majority of people, changing their BMI is very difficult if they had a high BMI throughout childhood,” says Jennifer Lyn Baker.

Research to be followed up

Jennifer Lyn Baker says that the research project has not yet been completed because the researchers still need to determine whether a high childhood BMI trajectory increasing the risk of developing risk markers for cardiovascular disease also results in developing a cardiovascular disease, such as a stroke or a heart attack.

The evidence suggests this, but the researchers need to confirm or refute this hypothesis.

“Our next research project will investigate how each childhood BMI trajectory is associated with an adult’s risk of not only having a stroke or a heart attack but also developing type 2 diabetes or cancer,” says Jennifer Lyn Baker.

Associations between body mass index trajectories in childhood and cardiovascular risk factors in adulthood” has been published in Atherosclerosis. Several co-authors are employed at Steno Diabetes Center Copenhagen or the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, both of which receive grants from the Foundation.

Jennifer L. Baker is the leader of the Lifecourse Epidemiology group in the Section of Clinical Epidemiology at the Center. Jennifer received her PhD...

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