Higher levels of insulin‐like growth factor‐1 in cord blood associate with risk of asthma at age 3

Rationale Experimental studies and epidemiological data in adults suggest that somatomedin‐C (insulin‐like growth factor‐1, IGF‐1) may play a role in asthma by modulating airway inflammation, bronchial hyperreactivity, and airway smooth muscle hyperplasia. However, its role in children with asthma is not well understood. Methods We established a birth cohort with 339 Chilean pregnant mothers enrolled at the time of delivery from December 2014 to January 2016. We obtained cord blood at birth and followed the offspring every 6 months until 30 months of age, recording data on atopy, wheezing, and other respiratory illnesses. We measured IGF‐1 in cord blood and determined the Asthma Predictive Index (API) at 30 months. The cohort was divided according to the API. Results Complete data were available for 307/339 (91%) dyads, including 44 preschoolers with API+ and 263 with API–. Demographic characteristics were similar between groups, but mothers of API+ children had a higher prevalence of obesity, previous use of oral contraceptives, and higher education than those of API– children. API+ children had higher birth weight and significantly higher IGF‐1 in cord blood (37.4 ± 13.2 in API+ vs. 30.5 ± 13.0 ng/ml in API–, p = .01). In the multivariable analysis, IGF‐1 in cord blood remained independently associated with a higher risk of asthma (adjusted OR for API+ per ng/ml higher IGF‐1 = 1.03 [1.0–1.06], p = .015). Conclusions Higher insulin‐like growth factor‐1 in cord blood is associated with asthma risk in the preschool years.