Excessive gestational weight gain increases risk of childhood asthma, rhinitis, and allergic sensitization: evidence from a Birth Cohort

Background Maternal body mass index (BMI) before pregnancy and gestational weight gain (GWG) have been implicated in offspring health, yet their specific impact on the development of allergic diseases remains unclear. We aimed to evaluate associations between pre-pregnancy BMI and GWG with asthma, rhinitis, eczema, food allergy, anaphylaxis, and allergic sensitization during childhood and adolescence. Methods We analyzed 7280 mother-child pairs from Generation XXI, a Portuguese population-based birth cohort. Maternal BMI was categorized per World Health Organization criteria and grouped into underweight/normalweight vs.overweight/obesity. GWG was considered using Institute of Medicine (IOM) guidelines and GWG z-scores. Allergic outcomes were assessed via parent-reported physician diagnosis at 4, 7, 10, and 13 years, and allergic sensitization was determined at 10 years using ImmunoCAP. Associations were analyzed using logistic regression models adjusted for confounders. Results Children of mothers with excessive GWG had increased odds of asthma at ages 7 and 13 (aOR=1.30; 95%CI 1.01-1.66 and aOR=1.29; 95%CI 1.01-1.65, respectively), and rhinitis at 4 (OR=1.48; 95%CI 1.10-1.98). Higher GWG z-scores were associated with increased odds of asthma (aOR=1.33; 95%CI 1.03-1.72), rhinitis (aOR=1.54; 95%CI 1.13-2.09), and sensitization (aOR=1.44; 95%CI 1.05-1.97). Lower GWG z-score was associated to higher eczema odds at 13, while higher GWG z-score reduced eczema odds at age 4. Maternal overweight/obesity was associated with lower odds of eczema at age 13 (aOR=0.73; 95%CI 0.60-0.88). Conclusion Higher GWG is associated with increased odds of childhood asthma, rhinitis, and sensitization. In contrast, maternal overweight/obesity is linked to lower odds of eczema, suggesting condition-specific effects of maternal weight on childhood allergy risk.