['D-dimer levels have been reported to increase progressively during pregnancy, but how this affects Nigerian women is not well known.', 'This study aims to determine the D-dimer concentration and its relationship to other coagulation parameters among pregnant women in Port Harcourt, Nigeria.', 'In a cross-sectional observational study conducted in Port Harcourt, Nigeria, 120 pregnant women and 60 nonpregnant controls, drawn from a tertiary health institution in the Niger Delta, Nigeria, were assessed, using the standard procedures, for the following parameters: D-dimer concentration, prothrombin time, activated partial thromboplastin time, platelet count, hemoglobin, and packed cell volume.', 'The median D-dimer concentration of 153.1 ng/mL in the pregnant group was found to be significantly elevated when compared with the control value of 118.5 ng/mL (t = 2.348, P = 0.021). Conversely, there was a marked depression in the platelet count among pregnant women (193.5 × 10(9)/L) when compared with 229.0 × 10(9)/L in the control group (t = 3.424; P = 0.001). There was no statistically significant difference in the values for the prothrombin time and the activated partial thromboplastin time between pregnant and nonpregnant women. D-dimer values correlated positively and significantly with gestation (r = 0.36; P < 0.01) and negatively with international normalized ratio values (r = -0.281; P < 0.05). About 63.3% of the pregnant women had normal D-dimer values (0-200 ng/mL), 26.7% of the pregnant women had elevated D-dimer levels (201-499 ng/mL), while 10.0% of the pregnant women were found to be at risk of thrombosis (D-dimer > 500 ng/mL). A linear relationship was found to exist between D-dimer and gestation (y = 8.355x + 36.55; R(2) = 0.130; P < 0.005).'] Is elevation in D-dimer concentrations positively correlated with gestation in normal uncomplicated pregnancy?