Investigations on incidence and relevant factors of allergies in 5725 urban pregnant women: a cohort study in China

Allergic diseases are highly prevalent in the women of childbearing age. As we know, the immune system could change when pregnancy, which may affect the course of allergic diseases. Meanwhile, they also can affect the course and outcome of pregnancy. The data on incidence of allergies during pregnancy is lacking and conducting clinical trials in pregnant women was limited, therefore, we observed a prebirth cohort to supplement the relevant data and strengthen concerned research conductions. We aim to obtain the incidence of allergies in urban pregnancy and explore the relevant factors of allergic diseases in urban pregnancy. We design a multicenter and prospective cohort in 20 institutions above municipal level which were eligible according to the study design from 14 provinces covering all-side of China. This cohort was conducted from 13 weeks of gestation to 12 months postpartum and in our study, we chose the prenatal part to analyze. The outcome was developing allergies during pregnancy, which were diagnosed by clinicians according to the uniform criterion from National Health Commission. All the data was collected by electronic questionnaires through tablet computers. The incidence of allergic diseases in urban pregnant women was 21.0% (95%CI 20.0% ~ 22.0%). From social demography data, the history of allergies of pregnant women and their parents had statistical significance(p