INTRODUCTION
Gestational diabetes mellitus (GDM) is defined as diabetes that is diagnosed in the second or third trimester of pregnancy and not overt prior to gestation (1). Over the past decade, the prevalence of GDM has been on the rise (2). In 2013, International Diabetes Federation (IDF) conducted a comprehensive survey based on the data from 47 epidemiological studies in 34 countries and regions around the world. The global prevalence of hyperglycemia in pregnant women (20-49 years) was 16.9%, and that of GDM was 14.2% for the same group; about 21.4 million live births showed signs related to maternal hyperglycemia (3). The incidence of GDM varies with countries, and all show an upward trend.
GDM causes adverse events both in women and children , such as maternal type 2 diabetes and obesity in children (4, 5). Previous epidemiological studies have found that GDM may increase the risk of childhood allergic diseases, including asthma and atopic dermatitis (6, 7). Current population-based research results are inconsistent. Delayed pneumocyte differentiation and lung maturation were observed in the offspring in rodent models of diabetes during pregnancy (8-11). The possible mechanism for their pathogenesis is that phosphatidylglycerol production may be inhibited in gestational diabetes, resulting in reduced surfactants and increased susceptibility to respiratory distress syndrome, which may also explain the increased risk of persistent wheezing in human infants born to women with GDM (12).
Food allergy, wheezing, asthma and eczema are the most common allergic disorders in children (13). Four endpoints were set in the present study: asthma, atopic dermatitis, food allergy and wheezing. To date, their association with GDM has not been systematically reviewed, and the results of existing studies on the association are inconsistent. Thus, we conducted a meta-analysis to evaluate the findings of previous epidemiological studies.