Inclusion criteria
1. Epidemiological studies based on human populations, such as cohort studies, case control studies and cross-sectional studies that identify the association between gestational diabetes mellitus and allergic diseases in the children.
2. Exposure factors relating to GDM.
3. Outcomes relating to allergic diseases in children born to GDM women, including atopic dermatitis, food allergy, asthma, and wheezing.