A 30-Year-Old Woman Comes to the Office for Preconception Counseling

A 30-year-old woman comes to the office for preconception counseling.  She has a history of rheumatic heart disease and underwent mechanical mitral valve replacement 5 years ago.  The patient has been taking warfarin and low-dose aspirin since the procedure and has had no complications or adverse reactions.  She has no history of other chronic medical conditions or surgeries.  The patient recently began taking folic acid daily and is planning on discontinuing her progestin-releasing intrauterine device in the next few months.  She does not use tobacco, alcohol, or illicit drugs.  Family history is significant for a grandmother with a recent hip replacement complicated by a postoperative pulmonary embolism.  Blood pressure is 110/70 mm Hg and pulse is 78/min.  BMI is 23 kg/m².  Physical examination is without abnormalities, other than a large sternotomy scar.  The patient expresses concern about the possible adverse effects of warfarin on the baby and her pregnancy.  Which of the following is the most appropriate recommendation for this patient?

A) Anticoagulation can be discontinued during pregnancy as no postoperative thrombotic events have occurred but should be restarted postpartum.
B) Warfarin can be continued throughout the pregnancy, but aspirin should be discontinued.
C) Warfarin should be replaced with low-molecular-weight heparin before conception, throughout the pregnancy, and during breastfeeding.
D) Warfarin should be replaced with low-molecular-weight heparin during the first trimester and with unfractionated heparin before delivery.
E) Warfarin should be replaced with unfractionated heparin throughout the pregnancy.