Changes in d-dimer levels in pregnant women according to gestational week

We performed a retrospective review of medical charts regarding blood d-dimer levels determined cross-sectionally by the latex agglutination assay in 1952 samples from 1185 women to determine changes in d-dimer levels according to the stage of pregnancy. Three of 17 women in whom further investigations were performed were found to have clinical venous thromboembolism (VTE). The median and 95th percentile values of d-dimer (μg/mL) in the 1182 women without clinical VTE, 0.54 and 2.41 at gestational week (GW) 4–13, increased gradually to 1.22 and 5.03 at GW 14–27, 1.81 and 6.18 at GW 28–35, and 2.13 and 5.85 at GW 36–42, respectively. A total of nine women (0.76%), including three women with clinical VTE, exhibited a d-dimer level >14.0 μg/mL, which was well above the 99th percentile for any stage of pregnancy. Thus, 3 (33%) of the nine with a d-dimer level >14 μg/mL developed clinical VTE, while none of the remaining 1176 women with a d-dimer level ⩽14 μg/mL developed clinical VTE. Although further prospective studies are required, our results suggested that there is a certain cut-off d-dimer value that would allow us to differentiate between pregnant women with and without clinical VTE.