5.0mg/L were randomly divided into LMWH treatment group and low molecular dextran treatment group with 20 patients in each group.The patients in LMWH group were treated with 0.3ml LMWH subcutaneous injection in abdominal wall in every 12h for 1-4 d.The patients in low molecular dextran group were treated with 500ml low molecular dextran plus 20ml danshen root,intervenous drop infusion for 1-7d.Results The D-Dimer blood serum level in the gestational late period was significantly higher than that of nongravida group(P