During pregnancy, every pregnant woman has to undergo a series of coagulation tests, of which D-dimer is an important part of the coagulation system. But the vast majority of women will find elevated D-dimer levels, the common reasons include the following: 1, physiological factors: pregnancy itself is in a mildly hypercoagulable state, it can be manifested as a mild increase in D-dimer during pregnancy, usually within 2 times above the normal range, but if the increase is particularly pronounced, for example, > 3-4 times above the normal range on line, we should consider the existence of pathological 2. Pathological factors: very high D-dimer levels usually indicate the presence of embolism in women, such as reduced protein C and protein S. In this case, other indicators should be checked, and if the presence of embolism is confirmed, anticoagulant drugs, such as aspirin and low molecular heparin, may be needed during pregnancy.