关键词: 糖尿病, 妊娠, 肺炎, 婴儿, 新生, 免疫功能

Abstract: Objective To investigate the relationship between the intestinal flora in the third trimester of pregnancy and the immune function of neonates in patients with gestational diabetes mellitus (GDM), and its impact on the susceptibility of neonates to infectious pneumonia. 
Methods A total of 245 patients with GDM in the third trimester of pregnancy admitted to our hospital were  selected, and divided into infection group (n=27) and non-infection group (n=218) according to the incidence of neonatal infectious pneumonia. Baseline data, maternal intestinal flora in the third trimester of pregnancy (Chao1 index, Shannon index, Bray Curtis distance), and neonatal immune function ［CD3+ T cells, CD4+ T cells, CD8+ T cells, immunoglobulin A (IgA) , immunoglobulin G (IgG), immunoglobulin M (IgM)］ of the two groups were compared. Pearson analysis was used to analyze the correlation between the intestinal flora in the third trimester of pregnancy and the neonatal immune function, and the multivariate Logistic regression equation was used to analyze the influencing factors related to neonatal infectious pneumonia. The receiver operating characteristic curve (ROC) and area under the ROC curve (AUC) were used to analyze the value of each index in predicting neonatal infectious pneumonia. 
Results There was a significant difference in blood glucose levels between the infection group and the non-infection group before delivery (P＜0.05). Chao1 index, Shannon index, CD3+ T cells, CD4+ T cells, CD8+ T cells, and IgG were lower in the infection group than in the non-infection group, while Bray Curtis distance was greater than that of the non-infection group (P＜0.05). After controlling the blood glucose level before delivery, the Chao1 index, Shannon index, Bray Curtis distance, CD3+ T cells, CD4+ T cells, CD8+ T cells, and IgG were still associated with the susceptibility to neonatal infectious pneumonia (P＜0.05). The AUC of Chao1 index, Shannon index, Bray Curtis distance, CD3+ T cells, CD4+ T cells, CD8+ T cells, and IgG in predicting neonatal infectious pneumonia was 0.754, 0.814, 0.771, 0.779, 0.817, 0.775, and 0.840, respectively (P＜0.05). 
Conclusion The intestinal flora of patients with GDM in the third trimester of pregnancy can affect the cellular and humoral immune functions of neonates, which are related to the susceptibility to neonatal infectious pneumonia, and can be used as a new method to predict neonatal infectious pneumonia. 

Key words: diabetes, gestational, pneumonia, infant, neonates, immune function