No anticoagulation strategy is optimally safe for both the mother and the fetus. Warfarin is saf- est for the mother but crosses the placenta and can cause fetal intracranial hemorrhage; fetal loss; and teratogenicity, particularly at doses >5 mg/d and when given during the first trimester, keeping in mind that the warfarin dose needed to maintain a therapeutic INR may change during pregnancy. Neither UFH nor LMWH crosses the placenta, but each is associated with higher rates of maternal complications than are seen with war- Depending on a woman s values and priorities, she may choose an antico- agulation strategy that minimizes maternal risk, minimizes fetal risk, or attempts to achieve a bal- ance between maternal and fetal risk. Physicians should not assume a woman s values or prefer- ences, nor should physicians supplant their own preferences for those of the patient. Counseling and shared decision-making allows for a woman and her physician to choose the best anticoagula- tion to achieve the woman s goals. 4. Warfarin crosses the placental barrier and results in anticoagulation of the fetus, as well as the mother. There is a higher risk of fetal intracra- nial hemorrhage if the mother is fully antico- agulated with warfarin during vaginal delivery. Women taking warfarin can minimize the risk Recommendations for Anticoagulation for Pregnant Women With Mechanical Prosthetic Heart Valves (Continued) COR LOE Recommendations CLINICAL STATEMENTS AND GUIDELINES Figure 18. Anticoagulation for prosthetic mechanical heart valves in women during pregnancy. Colors correspond to Table 2.*Dose-adjusted LMWH should be given at least 2 times per day, with close monitoring of anti-Xa levels. Target to Xa level of 0.8 to 1.2 U/mL, 4 to 6 hours after dose. Trough levels may aid in maintaining patient in therapeutic range. Continuous UFH should be adjusted to aPTT 2 times control. 