Hereditary thrombophilia and fetal loss: a prospective follow-up study.
BACKGROUND
As the placental vessels are dependent on the normal balance of procoagulant and anticoagulant mechanisms, inherited thrombophilia may be associated with fetal loss.


OBJECTIVE
We performed a prospective study to investigate the relation between inherited thrombophilia and fetal loss, and the influence of thromboprophylaxis on pregnancy outcome.


METHODS
Women were enrolled in the European Prospective Cohort on Thrombophilia (EPCOT). These included women with factor (F)V Leiden or a deficiency of antithrombin, protein C or protein S. Controls were partners or acquaintances of thrombophilic individuals. A total of 191 women (131 with thrombophilia, 60 controls) had a pregnancy outcome during prospective follow-up. Risk of fetal loss and effect of thromboprophylaxis were estimated by frequency calculation and Cox regression modelling.


RESULTS
The risk of fetal loss appeared slightly increased in women with thrombophilia without a previous history of fetal loss who did not use any anticoagulants during pregnancy (7/39 vs. 7/51; relative risk 1.4; 95% confidence interval 0.4, 4.7). Per type of defect the relative risk varied only minimally from 1.4 for FV Leiden to 1.6 for antithrombin deficiency compared with control women. Prophylactic anticoagulant treatment during pregnancy in 83 women with thrombophilia differed greatly in type, dose and duration, precluding solid conclusions on the effect of thromboprophylaxis on fetal loss. No clear benefit of anticoagulant prophylaxis was apparent.


CONCLUSIONS
Women with thrombophilia appear to have an increased risk of fetal loss, although the likelihood of a positive outcome is high in both women with thrombophilia and in controls.
Vossen
C Y
CY
Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
Preston
F E
FE
Conard
J
J
Fontcuberta
J
J
Makris
M
M
van der Meer
F J M
FJ
Pabinger
I
I
Palareti
G
G
Scharrer
I
I
Souto
J C
JC
Svensson
P
P
Walker
I D
ID
Rosendaal
F R
FR
D000293:Adolescent; D000328:Adult; D000925:Anticoagulants / Q000627:therapeutic use*; D004341:Drug Evaluation; D005192:Family Health; D005260:Female; D005313:Fetal Death / Q000209:etiology* / Q000517:prevention & control; D005500:Follow-Up Studies; D006801:Humans; D010920:Placenta / Q000098:blood supply; D011247:Pregnancy; D011256:Pregnancy Outcome; D011292:Premedication; D011446:Prospective Studies; D012044:Regression Analysis; D012306:Risk; D019851:Thrombophilia / Q000150:complications* / Q000235:genetics; D013927:Thrombosis / Q000188:drug therapy / Q000517:prevention & control
D000925:Anticoagulants