The study aims to evaluate the efficacy and safety of Colla corii asini (CCA ) in improve anemia during pregnancy among silent or standard α-thalassemia, HbH disease, minor or intermediate β-thalassemia. Four hundred and eighty pregnant patients who meet inclusion criteria will be randomly assigned to either the treatment group or control group. Patients in the treatment group will be given 15 g of CCA daily for 8 weeks and followed up to 42 days postpartum, while the control group were observed and followed up in the same period treated with placebo. Levels of hemoglobin (Hb),reticulocyte (RET), immaturity reticulocyte (IRF), indirect bilirubin (IBIL), total bilirubin (TBIL), lactic dehydrogenase (LDH) will be measured on three visits (baseline, week 4 and week 8). The curative effect of TCM Syndrome( week 8) and undesirable pregnancy outcomes(42 days after giving birth) will be observed.