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Early, rapid growth in BMI increased risk for asthma

Rapid growth in BMI during the first 2 years of life increased the risk for asthma in children aged up to 6 years, according to researchers in Europe.

“Despite several prospective studies and reviews, there is an ongoing debate on how BMI or obesity and asthma in children are linked,” the researchers wrote in The Journal of Allergy and Clinical Immunology. “Longitudinal studies in childhood comprising large numbers of obese children and incident cases in asthmatic patients over childhood are lacking.”

The researchers evaluated data from 12,050 children who were enrolled in eight European birth cohorts on asthma and allergies. They then calculated BMI scores according to WHO child growth standards, and also the incidence of doctor-diagnosed asthma. More than 51% of children were in the normative trajectory class for BMI (class 1), which is used as the reference class. About 47% of children were in class 2: rapid gain during the first 2 years of life, then a slightly higher BMI. In class 2, which included about 2% of the children, children had a steep BMI increase in the later 4 years of life, and had a high BMI at aged 6 years.

Overall, the percentage of incident asthma events was 4.1% in the first 2 years of life, 2.8% from aged 3 to 4 years, and 2.5% from aged 5 to 6 years. Children in class 2 had a higher risk for incident asthma up to age 6 years, with an HR of 1.3 (95% CI, 1.1-1.5) after adjustment for birth weight, weight-for-length at birth, gestational age, sex, maternal smoking during pregnancy, breast-feeding and a family history of allergies and asthma. Rapid BMI increase from aged 2 to 6 years, besides the increase during the first 2 years, did not increase the risk for asthma.

“Because a persistent rapid BMI gain from birth to age 6 years did not have a statistically significantly stronger effect on incident asthma than gain only in the first 2 years of life, it might be concluded that early rapid BMI gain, within the first 2 years, contributes to the development of asthma in early childhood,” the researchers wrote. “Biological mechanisms behind this predictive association should be investigated further.”

Disclosure: One researcher is employed by Charité Berlin.