[Study on the dynamic changes of D-dimer during pregnancy and early puerperium]

Objective: To explore the dynamic changes of D-dimers during pregnancy and early puerperium(within 3 days postpartum). Methods: A retrospective study was performed among 8 367 healthy women who had term singleton delivery in Women's Hospital, School of Medicine, Zhejiang University from January 2007 to December 2014. D-dimers concentrations during pregnancy and early puerprium of all the cases were collected. Data of 21 065 D-dimers tests were assigned to 5 groups according to the time of sampling, including early pregnancy(≤12 gestation weeks), middle pregnancy(12-28 gestation weeks), late pregnancy(>28 gestation weeks), 1 postpartum(within 48 hours postpartum)and 2 postpartum(48- 72 hours postpartum). The D-dimers concentrations in different groups were compared. The effect of delivery mode on D-dimers of early pureperium was analyzed. The correlation between D-dimers and the thromboembolic disease was also explored. In this study, Student's t-test and Wilcoxon rank sum test were used for statistical analysis. D-dimers concentration ≤0.5 mg/L was used as the normal range. Results: (1)D-dimers concentrations during pregnancy were higher than the non-pregnant women(P<0.01), but there was no statistical difference between early pregnancy and late pregnancy(P=0.820). D-dimers concentration in the 1 postpartum group was higher than that of early pregnancy group or late pregnancy group(P<0.01). But in the 2 postpartum group, it was lower than early pregnancy, late pregnancy and 1 postpartum groups.(2)D-dimers in cesarean section cases was significantly higher than in vaginal delivery cases in each period of pregnancy and early pueprium.(3)The 95%CI of D-dimers in early pregnancy, late pregnancy, 48 hours after vaginal delivery, 48- 72 hours after vaginal delivery, ≤48 hours after cesarean section, 48- 72 hours after cesarean section were 0.58-8.28, 0.47-11.52, 1.04-9.59, 0.87-5.22, 1.07-11.58 and 1.00-6.23 mg/L, respectively.(4)In 6 cases with thromboembolic disease, D-dimers was 6.89- 19.89 mg/L, with the mean value of 13.66 mg/L. It was significantly higher than normal range. In 3 cases, all after cesarean section, with lower extremity vein thrombosis within 48 hours postpartum, the D-dimers concentrations, 9.77, 8.65 and 6.89 mg/L respectively, were in the 95% CI of the study population after cesarean section. Conclusions: D-dimers concentration of 0.5 mg/L is not suitable for venous thromboembolism screening during pregnancy. D-dimers concentration in pregnancy and early puerprium is higher than non-pregnancy. It increases in the very early period postpartum and decreases with time. D-dimers should not be a routine screening test to exclude thromboembolic disease in pregnant women without high risk factors and clinical manifestation of thromboembolic disease.