Drinking too little water postpartum does not have much to do with the rise or fall of D-dimer, which mainly reflects the measurement of fibrinolytic activity. The normal value of plasma D-dimer should be 0-0.256mg/L. The main purpose is to encapsulate the D-dimer monoclonal antibody in the enzyme reaction plate and add it into the plasma of the examinee, and then after a series of reactions to see whether the plasma D-dimer is normal, which can reflect the fibrinolytic activity, and the elevation or decrease of D-dimer has no great relationship with drinking too little water after delivery. Elevated D-dimer can be seen in disseminated intravascular coagulation, acute promyelocytic leukemia, pulmonary thromboembolism, deep vein thrombosis, etc., and further examination is needed to find out the cause, and timely consultation for treatment, and the recovering mothers should get out of bed as soon as possible according to their own conditions, to promote the recovery of the body.