D-Dimer (DD) is the smallest fragment of plasmin-mediated cleavage of fibrin. There is a progressive increase in DD concentration with advancing gestation in normal pregnancies, making the upper limit of 0.5 mu g/ml used in non-pregnant population an unfavorable marker during pregnancy. Coagulation and fibrinolysis parameters are also markedly disturbed in pregnancies complicated by various pathologies. We designed this retrospective observational cohort study to investigate the trimester specific reference range for DD throughout normal pregnancy, and to compare the distribution of DD in third trimester healthy pregnancies and those complicated by preeclampsia (PE), severe preeclampsia (SPE), gestational diabetes mellitus (GDM), premature rupture of membranes (PROM) and preterm premature rupture of membranes (PPROM). In addition, we aimed to determine the diagnostic value of DD in PE and SPE. In this retrospective observational cohort study, 250 normal and 178 complicated pregnancies were included. Normal pregnancies included 88-first trimester, 101-second trimester and 61-third trimester pregnancies. Complicated pregnancy included 34 PE, 44 SPE, 32 GDM, 33 PROM, and 35 PPROM cases during the third trimester. Predefined exclusion criteria were used. The period of gestation (POG) accounted for 41.9% of the variance in DD, with strong correlation between the POG and DD. The trimester specific reference intervals were computed. The distribution for severe preeclampsia was statistically different compared to other categories in the third trimester. This exceptional distribution led to the generation of a receiver operating characteristic (ROC) curve with an area under curve of 0.828, attesting its possible role in predicting severe preeclampsia. We determined trimester specific reference intervals of DD. The role of DD has been explored, and it may be of diagnostic value in severe preeclampsia.