The PE in special populations page has been updated with particular reference to d dimer levels during pregnancy. Some relevant references are:
Greer, IA. Pregnancy Complicated by Venous Thrombosis. New England Journal of Medicine 2015;373(6):540-47. http://www.nejm.org/doi/full/10.1056/NEJMcp1407434.
Kline, JA, Williams, GW, Hernandez-Nino, J. D-dimer concentrations in normal pregnancy: new diagnostic thresholds are needed. Clin Chem 2005;51(5):825-9. http://www.ncbi.nlm.nih.gov/pubmed/15764641.
Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009 Dec;114(6):1326-31. PMID:19935037