480 pregnant patients diagnosed of silent or standard α-thalassemia, HbH disease, minor or intermediate β-thalassemia with mild anemia will be randomly assigned to treatment group and control group. Patients in the treatment group will be given 15 g of Colla corii asini powder form daily for 8 weeks and followed up to 42 days postpartum while the control group will be 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.