BackgroundThe high rates of obesity and suicide have become serious public health problems worldwide, especially in children and adolescents with major depressive disorder (MDD). This research aimed to explore the rates of underweight, overweight or obesity, suicidal ideation and attempted suicide in hospitalized children and adolescents with MDD. Then, we analyzed the correlation between underweight or obesity and suicidal ideation and attempted suicide, and finally obtained the independent influencing factors of underweight or obesity.MethodsA total of 757 subjects in the Third People’s Hospital of Fuyang from January 2020 to December 2021 were enrolled in this study. According to the underweight, overweight and obesity screening table for school-age children and adolescents published and implemented by the health industry standard of China, all subjects were divided into different body mass index (BMI) categories. We measured fasting blood glucose (FBG) and lipid levels in all subjects and assessed suicidal ideation, attempted suicide, and the severity of depressive symptoms. The socio-demographic and clinical data were collected and analyzed by SPSS 22.0.ResultsThe rates of underweight, overweight, obesity, suicidal ideation and attempted suicide were 8.2% (62/757), 15.5% (117/757), 10.4% (79/757), 17.2% (130/757), and 9.9% (75/757), respectively. Correlation analysis indicated that BMIs level was positively correlated with age, age of first hospitalization, total duration of disease, number of hospitalizations, FBG, TG (triglyceride), TC (total cholesterol), LDL (low density lipoprotein), and negatively correlated with HDL (high density lipoprotein). Binary logistic regression analysis showed that male and high level of HDL were risk factors for MDD inpatients with underweight, while high level of TG was a protective factor. Meanwhile, higher levels of FBG, TG and CGI-S were risk factors and suicidal ideation and high dose of antidepressant drugs were protective factors for obesity in children and adolescents with MDD.ConclusionThe prevalence of underweight, obesity, suicidal ideation and attempted suicide were high in children and adolescents with MDD, and severe depressive symptoms are independent risk factors for obesity, while suicidal ideation and high dose of antidepressants may be protective factors for obesity.