Coagulation and fibrinolysis in smoking and nonsmoking pregnant women

OBJECTIVES: To assess the effects of smoking during pregnancy on coagulation and fibrinolysis. DESIGN: A cross-sectional study. SETTING: A teaching hospital in Heerlen, The Netherlands. RESULTS: Parameters of coagulation activation increased significantly with gestational age. The values presented are median values. Prothrombin fragment 1 + 2 increased from 0.8 to 2.5 nmol/l in the nonsmoking group of pregnant women and from 1.0 to 1.8 nmol/l in the smoking group. Thrombin-antithrombin III (TAT) levels increased from 2.2 to 9.9 micrograms/l in the nonsmoking group and from 3.1 to 8.5 micrograms/l in the smoking group. Parameters of fibrinolysis showed a different picture. Plasminogen levels in both groups rose significantly in the first half of gestation reaching a plateau in the second half. The alpha 2-antiplasmin levels remained constant in both groups, although the smokers started with significantly higher levels: 119 versus 105% in the nonsmokers. The D-dimer levels rose significantly in both groups: from 278 to 847 micrograms/ml in the nonsmokers and from 215 to 520 micrograms/ml in the smokers. They were significantly lower in the smoking group from the 11th up to the 40th weeks. The D-dimer/TAT ratio was significantly higher in the nonsmokers. CONCLUSIONS: In smoking pregnant women the activated coagulation process was not counter balanced by an adequate increase of fibrinolysis which was the case in the nonsmokers.