Blood clots in pregnancy.

Pregnant women's risk of venous thromboembolism--blood clots forming in deep veins, which may travel to the lungs--appears to begin early in gestation, according to findings from a multisite study of the condition conducted in 2001-2002. (1) Of the 5,541 individuals enrolled in the study, 34 were pregnant women and 19 were women who had recently given birth. Nearly half of the pregnant women (15) had developed a deep vein thrombosis during their first trimester. One of the pregnant woman and 14 of the postpartum women had undergone surgery within the three months before diagnosis; eight and one, respectively, had a genetic predisposition to the condition, but for most women in both groups, this was its first occurrence. Pregnant women were hospitalized for an average of 6.4 days to treat acute deep vein thrombosis, and postpartum women were hospitalized for an average of 9.1 days. Noting that prevention and treatment of venous thromboembolism among pregnant women "may reduce maternal morbidity and mortality and improve the outcome of pregnancy," the investigators conclude that "when prophylaxis is indicated, it should be initiated early in pregnancy."

(1.) James AH, Tapson VF and Goldhaber SZ, Thrombosis during pregnancy and the postpartum period, American Journal of Obstetrics and Gynecology, 2005, 193(1):216-219.