D-dimer during pregnancy: establishing trimester-specific reference intervals

Scand J Clin Lab Invest. 2018 Oct;78(6):439-442. doi: 10.1080/00365513.2018.1488177. Epub 2018 Jul 5.


Pregnancy is associated with an increased risk of venous thromboembolism (VTE). D-dimer is a biomarker used as an exclusion criterion of VTE disease, but its usefulness during pregnancy shows limitations because D-dimer levels physiologically increase through pregnancy. The aim of our study was to follow the changes of D-dimer levels and to establish trimester-specific reference intervals during normal pregnancy. This is a longitudinal prospective study in which the reference population finally included 102 healthy pregnant women. Plasma D-dimer levels were measured during the three trimesters of pregnancy, using a latex-based immunoturbidimetric assay. Reference intervals were calculated according to the Clinical and Laboratory Standards Institute recommendations. D-dimer levels increased progressively and significantly through pregnancy and peaked in the third trimester, in which D-dimer levels were above the conventional cut-off point (500 µg/L) in 99% of pregnant women. The following reference intervals were defined: first trimester: 169-1202 µg/L, second trimester: 393-3258 µg/L and third trimester: 551-3333 µg/L. The study provides reference intervals of D-dimer during the pregnancy using latex-based immunoturbidimetry on the ACL 300 TOP automated coagulation analyser. Further prospective studies of pregnant women with clinical suspicion of VTE are needed to validate these results.

Keywords: D-dimer; gestational age-specific reference intervals; pregnancy; trimesters; venous thromboembolism.

MeSH terms

  • Adult
  • Biomarkers / blood
  • Blood Chemical Analysis
  • Female
  • Fibrin Fibrinogen Degradation Products / analysis*
  • Humans
  • Pregnancy
  • Pregnancy Trimesters / blood*
  • Prospective Studies
  • Reference Values
  • Venous Thromboembolism / blood


  • Biomarkers
  • Fibrin Fibrinogen Degradation Products
  • fibrin fragment D