Recent research suggests that asthma may originate through defects in the airway epithelium, acquired in utero, and an altered response to infections after birth. Here, we examine whether asthma in adult life is associated with reduced body size at birth and poor living conditions in childhood.
We studied 658 people taking medication for asthma in a cohort of 13 345 men and women born in Helsinki, Finland, during 1934–1944. Their body and placental size at birth, and their living conditions and growth in childhood, had been recorded.
The odds ratios for asthma were 0.93 (95% CI 0.89–0.97, p = 0.001) per cm increase in birth length and 0.92 (0.89–0.96, p < 0.001) per cm increase in the length of placental surface. After allowing for size at birth, growth during childhood was unrelated to asthma. People who were born into families of low socio-economic status were at increased risk of later asthma.
Slow linear growth in utero, which could be a result of impaired placentation, increases the risk of later asthma. Slow linear growth may be associated with impaired development of the airways. Babies with impaired lung development born into families of low socio-economic status may be most vulnerable to the disease.