Contrasting associations of maternal smoking and pre-pregnancy BMI with wheeze and eczema in children

Highlights: • In a prospective birth cohort, we estimated the effects of prenatal maternal smoking and her pre-pregnancy BMI on the prevalence of three allergic diseases in the offspring including wheeze, rhinoconjunctivitis, and eczema at age 1, 2, 4, and 7 years (n = 3296). • Prenatal factors such as prenatal maternal smoking and high BMI may result in increased risk of wheezing and potential development of asthma in the next generation. • Prenatal maternal BMI, but not childhood BMI at age 7, was associated with increased and decreased risk of wheeze and eczema at age 7, respectively, in a dose-response manner. • Associations of prenatal maternal smoking and BMI on postnatal allergic conditions were independent of each other. • For precise assessment of allergy-associated risk factors, we need to contrast risk factors for different allergic diseases since focusing solely on one allergic disease may result in misleading information on the role of different risk factors. Childhood allergies are dynamic and associated with environmental factors. The influence of prenatal maternal smoking and obesity on childhood allergies and their comorbidities remains unclear, especially in prospective cohorts with serial longitudinal observations.