Effects of Vitamin D and Prebiotic Supplementation on Glucose Control During Pregnancy

Inclusion Criteria: 1. 6-15 weeks of gestation. 2. Age 18-45 years old. 3. Permanent resident or resident locally at least one year. 4. GDM high-risk pregnant women (meeting any of the following criteria): 1. Pre-pregnancy body mass index (BMI) ≥24.0 kg/m2, 2. History of GDM or a family history of diabetes, 3. History of delivery of macrosomia (birth weight \>4000 g), 4. HbA1c 5.7-6.4% or fasting blood glucose 5.6-7.0 mmol/L. Exclusion Criteria: 1. Multiple pregnancy. 2. Have received infertility treatment such as in vitro fertilization or intrauterine insemination. 3. History of diabetes or current diagnosis of diabetes (including type 1 and type 2 diabetes) or abnormal glucose tolerance at recruitment (fasting blood glucose \>7.0 mmol/L or HbA1c≥6.5%). 4. Serious chronic diseases (including cardiovascular and cerebrovascular diseases, cancer, and thyroid dysfunction) or infectious diseases (including hepatitis B, active tuberculosis, acquired immunodeficiency syndrome, and syphilis). 5. Severe liver disease (such as cirrhosis) or severe kidney disease (such as renal failure or requiring dialysis). 6. Kidney stones, hypercalcemia, hypercalciuria, parathyroid hormone abnormality. 7. Any mental disorders, such as schizophrenia, depression, other mental disorders, or bipolar disorder. 8. History of allergy or intolerance to vitamin D, chicory root, or starch. 9. Have participated in or are participating in other clinical trials within the past 3 months. 10. Daily vitamin D intake \>800 IU. 11. Inability or refusal to answer and communicate. 12. Those who are unwilling to sign the informed consent. 13. The researcher thinks that it is not suitable to participate in this research.