The study aimed to clarify the characteristics of the intestinal and oral microbiome of Gestational Diabetes Mellitus(GDM) patients during the whole pregnancy, try to clarify the relationship between the microbiome and GDM.

The aims of the study are to reveal the possibly natural change of the gut and oral microbiome of GDM patients during pregnancy, and to explorer whether GDM happened during pregnancy are associated with the maternal gut and oral microbiomes. As a perspective cohort study, the researchers will recruit pregnant women in early pregnancy（before 13 gestational weeks）and following the pregnancies till delivery. The stool samples and saliva samples of the recruits will be collected in 9~14,24~28 and 32~37 gestational weeks separately. The investigators will also perform oral examination between 24~28 weeks and sample subgingival plaque for test. Overall, all samples will be examined use 16S rRNA gene sequencing to analyze microbiome. And part of the samples of GDM patients will be analyzed using metagenomics. Combine with the pregnancy outcomes, the differences of gut and oral microbiome between GDM patients and healthy women will be expected, as well as the natural change during pregnancy.

Inclusion Criteria:

• pregnant women
• gestational age: before 13+6 weeks
• regular prenatal care in PUMCH

Exclusion Criteria:

• have medical history or current conditions： Gastrointestinal disorders, for example: Gastritis, gastric ulcer, inflammatory bowel disease; Hypertension; Diabetes; SLE or other severe CTD;
• pregnant, combine with malignancy diseases;
• pregnant, can't ensure regular prenatal check.

pregnant women who can ensure a regular prenatal check in the PUMCH OB clinic.