Coagulation factor XIII in pregnant smokers and non-smokers.

Human blood coagulation factor XIII is a transglutaminase zymogen. Two forms exist, an extracellular or plasma factor XIII and an intracellular form. Factor XIII occurs in platelets, blood, monocytes, megakaryocytes, the liver, the placenta, and the uterus. In obstetrics, factor XIII deficiency has been associated with fetal wastage. The interaction of smoking and the quantity of coagulation factor XIII during normal pregnancy was examined in 75 non-smoking and 118 smoking (> or = 20 cigarettes/day) women. A group of subjectively healthy, non-smoking, age-matched females served as a control group (n = 30). Smokers had a higher plasma concentration of factor XIII than non-smokers. Factor XIII declined during normal gestation. During the second half of gestation the plasma concentration of factor XIII was significantly higher in smokers than in non-smokers. In smokers the decline of factor XIII was less, possibly due to platelet activation and a relative polycythemia. The later decline of factor XIII in pregnant smokers remains unexplained. More extensive research with larger patient numbers is needed to address this matter.