Oral And Intestinal Microbial Features In Pregnant Women With Hypothyroidism And Their Correlations With Pregnancy Outcomes

ObjectiveHypothyroidism during pregnancy is a common complication of pregnancy,whichleads to a significant increase in the incidence of premature delivery,abortion,hypertension during pregnancy,placental abruption,intellectual development disorders and even fetal death in neonates^[1].Studies have found that the occurrence and development of hypothyroidism during pregnancy is closely related to inflammation,immune and metabolic function^[2,3].The current treatment for this disease is mainly based on regular oral thyroid hormone supplementation,but individual differences and the dynamics of thyroid hormones in pregnant women during pregnancy makes the control of thyroid function of lots of pregnant women is still poor.Current studies believe that the intestinal microbiota is closely related to the host’s various immune,metabolic and inflammation changes^[4-6],and the correlation between the intestinal microbiota and hypothyroidism has also been proven^[7].However,the research on the relationship between oral microbiota and hypothyroidism is still insufficient,especially the exploration of hypothyroidism during pregnancy is even rarer.Therefore,this article will conduct 16S r RNA gene amplification and sequencing on the saliva and stool samples of the subjects to describe the differences in the structural composition and abundances of the oral and intestinal microbiota of pregnant women with hypothyroidism during pregnancy and pregnant women with normal thyroid function,and look for the biomarkers of the two groups.The biomarkers between the different microorganisms and the clinical information of the host are analyzed,aiming to explore the characteristics of the oral and intestinal microbiota of the pregnant women with hypothyroidism during pregnancy and their correlation with the pregnancy outcome,providing some new ideas for the early detection and diagnosis and treatment of hypothyroidism during pregnancy.MethodsIn this study,16S r RNA sequencing was used to compare the species and abundance of oral and intestinal microbiota of 30 pregnant women with hypothyroidism during the third trimester（Group H）and 31 pregnant women with normal thyroid function（Group N）during the same period.Furthermore,serological indices and the pregnancy outcomes were added to the analysis to examine the links between oral and intestinal microbiota and pregnancy outcomes.Results（1）The dominant bacteria in oral of pregnant women in the two groups were Streptococcus,Neisseria,Prevotella and Haemophilus,while the dominant bacteria in intestine were Faecalibacterium,Bacteroides,Escherichia and Roseburia.（2）There was no significant difference ofαdiversity between the two groups in oral and intestinal microbiota,so does theβdiversity of intestinal microbiota,but there was significant difference inβdiversity between group H and group N in oral microbiota.（4）The Linear discriminant analysis Effect Size showed that the relative abundances of Proteobacteria,Gammaproteobacteria,Prevotella in the oral and intestinal tracts of pregnant women in group H were higher than those in group N,while the levels of Firmicutes,Bacilli and Clostridia in the control group were higher than those in the hypothyroidism group.Furthermore,the serum CRP level,the weight gain during pregnancy and the incidence of fetal distress in group H were higher than group N.In addition,Prevotella in intestine,Gammaproteobacteria and Haemophilus in saliva were positively correlated with the level of CRP and weight gain during pregnancy,while Gammaproteobacteria in saliva and Haemophilus in intestine were positively correlated with the level of thyroid stimulating hormone.ConclusionHypothyroidism during pregnancy is closely related to the oral and intestinal microbiota of pregnant women,and different biomarkers such as Haemophilus Prevotella may mediate the occurrence and development of hypothyroidism during pregnancy through inflammation and immunity pathways.