Does asymptomatic carriage of FV Leiden and FII prothrombin mutations in heterozygous configuration pose an increased risk of thrombembolic complications in the course of pregnancy, labor and puerperium?

Objective: To evaluate the course of pregnancy and puerperium in asymptomatic carriers of FV Leiden and FII prothrombin mutation in heterozygous configuration in terms of risk of thrombembolic disease (TED) and late pregnancy complications. To evaluate whether global prophylactic LMWH administration during pregnancy benefits these women.

Methods: We monitored the incidence of thrombembolic events and severe late pregnancy complications in 473 asymptomatic carriers of FV Leiden and FII prothrombin mutation in heterozygous configuration. In 253 women, preventive LMWH application was introduced already during pregnancy. In 220 women, the application of LMWH was commenced as late as on the delivery day. In both groups application of LMWH continued during the puerperium.

Results: The incidence of TED in the whole group of carriers of thrombophylic mutations accounted for 0.19%. The incidence of severe late pregnancy complications was low - 2.5% compared with general population of pregnant women (6.4%).

Conclusions: No direct causal relationship was established between asymptomatic carriage of Leiden and prothrombin mutation in heterozygous configuration and the occurrence of severe late pregnancy complications. There was no benefit from general LMWH prophylaxis started as early as pregnancy in these women and thus we consider it unnecessary.