Abstract: Objective：To investigate the effect of different doses of low-molecular-weight heparin on the pregnancy outcomes in those patients with preeclampsia history. Methods：The clinical data of 96 cases of re-pregnancy with preeclampsia history in our hospital were retrospectively analyzed. All patients were preventively treated with low-molecular-weight heparin, including 42 cases of group A (the low dose group, low molecular-weight-heparin calcium 2 500 U), 54 cases of group B (the high dose group, low-molecular-weight heparin calcium 5 000 U). The pregnancy outcomes, the blood coagulation function and renal function between the two groups were compared. Results：The pregnancy times of re-pregnancy in the two groups were longer than those of the previous pregnancy, and the incidences of severe complications were also significantly lower (both P＜0.05). However, there was no significant difference in the intrapartum and postpartum 24 h bleeding volume, when compared the re-pregnancy with the previous pregnancy (P＞0.05). There were no significant differences in pregnancy time, intrapartum and postpartum 24 h bleeding volume of re-pregnancy or the previous pregnancy, and the rates of severe complications, when compared between the two groups (P＞0.05). There was no significant difference in the incidence of preeclampsia between the two groups (16.67% vs. 22.22%, χ2=0.459，P=0.497). The rates of fetal growth restriction and neonatal asphyxia of re-pregnancy were lower than those of the previous pregnancy in the two groups, the rate of neonatal survival of re-pregnancy was higher than those of the previous pregnency (P＜0.05). There was no significant difference in perinatal outcome between the two groups (P＞0.05). There were no significant difference in PT, APTT, FIB, BUA and SCr between the two groups (P＞0.05). It was noteworthy that the 24 h urinary protein in the group B was significantly lower than that in the group A (P＜0.05). Conclusions：Prophylactic use of low-molecular-weight heparin improves maternal and perinatal outcomes of re-pregnancy in those women with preeclampsia history. The higher dose of low-molecular-weight heparin can be advised so as to lower the 24 h urinary protein.

Key words: Heparin, low-molecular-weight; , Pre-eclampsia, Pregnancy outcome, Dose characteristics