Long-term Follow-up on Childhood Adiposity After Randomized Controlled Lifestyle Interventions in Pregnancy - The FitKids Study

Worldwide obesity has nearly tripled since 1975. In 2020, 39 million children under the age of five were overweight or obese. In Denmark approximately 13% of children are overweight or severely overweight by the time they start school.

Overweight is generally defined as abnormal fat accumulation and obesity as excessive fat accumulation that may impair health. For children under five years of age, overweight is defined as weight-for-height greater than two standard deviations above World Health Organization (WHO) Child Growth Standards median. Obesity is defined as weight-for-height greater than three standard deviations above the WHO Child Growth Standards median. Childhood obesity is associated with an increased risk of adult obesity, type 2 diabetes, metabolic syndrome, early death and reduced mental health. The large scale of obesity and the serious health problems associated with it calls for more knowledge within the field to prevent children from becoming overweight.

Body growth, physical activity, diet, and mental health are focus areas with respect to prevention and treatment of childhood obesity. Current knowledge about both pre- and postnatal factors indicates that being exposed to an adverse fetal environment, including maternal obesity, enhances propagation of obesity and associated cardiometabolic comorbidities, including type 2 diabetes. Still, the evidence is inconsistent and leaves most questions unanswered.

Many studies have found strong associations between maternal BMI and their child's BMI. One study showed distinct differences between associations of child BMI with maternal BMI compared to paternal BMI at birth but with the difference between associations diminishing over time. Another study showed associations between maternal pre-pregnancy BMI and child BMI at age five - six years of age. Given this it seems reasonable to suggest that the intrauterine environment is likely associated with the growth trajectory of the young child.

It is known that intrauterine exposure to diabetes and size at birth are risk factors for developing type 2 diabetes mellitus later in life, but several studies have also shown that children of mothers with obesity and overweight/obese children are at risk of having early markers of metabolic syndrome, i.e., increased insulin resistance, disturbed lipid profiles and high blood pressure.