In Reply

In the 2006 study reported by Schaefer et al, the embryopathy rate was 0.7% in women taking phenprocoumon. A risk existed only where oral anticoagulants (OAC) were administered beyond the 8th week of gestation after the last menstruation. If the drugs were administered before the 8th week of gestation, no risk for embryopathy existed but the risk for miscarriage trebled compared with the risk in women not taking OAC (24% vs 9%).

The dose dependency of the embryopathy rate was studied in warfarin; equipotent dosages of other coumarins are not likely to have a different effect.

OAC provide the safest protection against valve thrombosis and thromboembolism, before and during pregnancy. 2.4% of women who were treated with OAC during their entire pregnancy developed thromboembolism, compared with 7% of those treated with low molecular weight heparins (LMWH). When LMWH were given only during the first trimester, the rate was 3.6% (2). According to Oran (2004), the rate of valve thrombosis when taking LMWH for the entire pregnancy was 9%. To ensure protection against valve thrombosis and thromboembolisms is the supreme aim in the care and information given to women with mechanical heart valves during pregnancy, as valve thrombosis is associated with high mortality for the mother as well as the fetus. Since the time interval from planning the pregnancy to conception is unpredictable, women should not be switched to a LMWH before conception. In the absence of urgently needed randomized studies, the recently published guideline from the European Society of Cardiology (Regitz-Zagrosek 2011) will be greatly helpful for doctors in deciding how to handle the complex problems of anticoagulation in pregnant women.

DOI: 10.3238/arztebl.2011.0621b

Dr. med. Christa Gohlke-Bärwolf

Ballrechten-Dottingen

Prof. Dr. med. Vera Regitz-Zagrosek

Geschlechterforschung in der Medizin und Center for Cardiovascular Research

Charité – Universitätsmedizin Berlin

Conflict of interest statement

Professor Regitz-Zagrosek holds patents in Roche Diagnostics, has received reimbursements for continuing medical educational events from Berlin Chemie, Bayer, and Willmar Schwabe, and has received research funding from Crataegus and Willmar Schwabe. Dr Gohlke-Bärwolf declares that no conflict of interest exists.