Effect of HCQ Combined With LT4 on LBR in Euthyroid Women With URPL and TPO-Ab

Inclusion criteria: 1. Women with history of two or more pregnancy loss with the same male partner (including biochemical pregnancies). 2. Karyotype analyses show no pathological abnormalities in each individual of the recruited couple. 3. Women aged between 20 and 40 years old (including 20 and 40). 4. Lupus anticoagulant (LA), anticardiolipin antibody (ACA), and anti-beta2-glycoprotein I antibodies (anti-β2-GP1 Ab) tests are all negative. 5. It is confirmed by ultrasound or hysteroscopy that there are no pathological lesions that affect the morphology of the uterine cavity (such as submucosal uterine fibroids, uterine malformations). 6. TPO-Ab positive (TPO-Ab \> 60 IU/mL using the Siemens kit of electrochemiluminescence method, or TPO-Ab \> 34 IU/mL using the Roche kit of chemiluminescence method). 7. Biochemically euthyroid. TSH, free triiodothyronine (FT3), and free thyroxine (T4) are all within the reference range of corresponding laboratory testing in each research center. Exclusion criteria: 1. Rheumatic diseases, such as systemic lupus erythematosus, undifferentiated connective tissue disease, etc. 2. Metabolic or endocrine diseases, such as diabetes. 3. Abnormal renal function: plasma creatinine level ≥130 μmol/L or abnormal liver function: alanine aminotransferase ≥80U/L or aspartate aminotransferase ≥80U/L. 4. Hypertension and malignant tumors. 5. Under treatment with glucocorticoids or immunosuppressor, including cyclosporine, azathioprine, prednisone, and methylprednisolone. 6. Body Mass Index (BMI) \>28kg/m2. 7. Past history of hyperthyroidism, hypothyroidism, and thyroid malignant tumors; 8. Allergy to 4-aminoquinoline compound, or those with retinal or visual field lesions caused by 4-aminoquinoline compound.