Neonatal size in term children is associated with asthma at age 7, but not with atopic dermatitis or allergic sensitization

Background: We hypothesized that anthropometrics in the newborn is associated with development of asthma later in life.

Methods: The study included a prospective, longitudinal clinical study of a birth cohort of 411 Danish neonates born at term of mothers with a history of asthma. The primary endpoint was physician-diagnosed asthma at age 7 years. Allergic sensitization and atopic dermatitis (AD) were also investigated. Infant size was measured at the research clinic on four occasions during the first year of life. Risk for asthma, AD, and allergic sensitization at age 6-7 were estimated from logistic regression. Time to first asthma and AD were investigated by Cox regression. Multivariate models were adjusted for gender, gestational age, and mothers smoking during pregnancy.

Results: Neonatal weight, length, body mass index and head circumference (z-score) were all significantly associated with asthma at age 7. Adjusted odds ratio for asthma by estimated birth weight z-score: 1.87 [1.23-2.84]; P = 0.004. Adjusted HR for onset of asthma by neonatal weight z-score: 1.46 [1.08-1.96]; P = 0.013. Neonatal size did not associate with AD or allergic sensitization.

Conclusions: Increased neonatal size was significantly associated with asthma at age 7 but not AD or allergic sensitization in at-risk children born at term. The findings suggest some common prenatal mechanisms linking body size and asthma.