From the Guidelines
Low molecular weight heparins (LMWHs) are the preferred anticoagulant for women trying to conceive or during pregnancy, as they do not cross the placenta and have not been associated with adverse effects on fertility or implantation, whereas vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) should be avoided due to their potential to cause embryopathy, fetal bleeding, and limited safety data. The effects of LMWHs, VKAs, and DOACs on conception, implantation, and fertility vary significantly. LMWHs, such as enoxaparin, are considered safe during conception and pregnancy because they do not cross the placenta and have not been linked to adverse effects on fertility or implantation 1. They are typically dosed based on weight, for example, enoxaparin 1mg/kg twice daily or 1.5mg/kg once daily.
Key Considerations for Anticoagulant Use in Pregnancy
- VKAs, like warfarin, should be avoided during conception attempts and pregnancy, especially during the first trimester, due to their ability to cross the placenta and cause embryopathy and fetal bleeding 1.
- Women on warfarin should switch to LMWH before conception or immediately upon pregnancy confirmation.
- DOACs (rivaroxaban, apixaban, edoxaban, dabigatran) are not recommended during conception attempts or pregnancy due to limited safety data and concerns about placental crossing 1.
- Women taking DOACs who wish to conceive should transition to LMWH before attempting pregnancy.
Recommendations for Clinical Practice
- LMWHs are the preferred choice for anticoagulation in pregnant women or those trying to conceive due to their safety profile and effectiveness.
- Close monitoring and adjustment of LMWH doses may be necessary as pregnancy progresses to ensure adequate anticoagulation and minimize risks.
- The use of VKAs and DOACs in pregnancy should be approached with caution, and alternative anticoagulants should be considered whenever possible.
- Further research is needed to fully understand the safety and efficacy of anticoagulants during pregnancy, particularly for DOACs and fondaparinux 1.
From the Research
Effects of Anticoagulants on Conception, Implantation, and Fertility
- The provided studies do not directly address the effects of Low Molecular Weight Heparin (LMWH), Vitamin K Antagonists (VKA), and Direct Oral Anticoagulants (DOACs) on conception, implantation, and fertility 2, 3, 4, 5, 6.
- However, it can be inferred that the use of these anticoagulants may have indirect effects on fertility, particularly in patients with underlying medical conditions such as cancer-associated thrombosis or mechanical heart valves.
- For example, a study on cancer-associated thrombosis found that LMWH was the preferred treatment option, with DOACs being used in some cases 4.
- Another study compared the effectiveness of DOACs and LMWH in treating cancer-associated thrombosis, finding that DOACs were effective but associated with a higher risk of bleeding 5, 6.
Anticoagulant Use in Pregnancy
- A study on anticoagulation regimens during pregnancy in patients with mechanical heart valves found that the use of VKA and LMWH had different effects on fetal and maternal outcomes 2.
- Another study discussed the management of venous thromboembolism in pregnancy, recommending the use of LMWH in therapeutic doses and continuing anticoagulation until 6 weeks after delivery 3.
Comparison of Anticoagulants
- The studies compared the effectiveness and safety of different anticoagulants, including LMWH, VKA, and DOACs, in various patient populations 4, 5, 6.
- The results suggested that DOACs may be an effective treatment option for some patients, but may also be associated with a higher risk of bleeding 5, 6.