Can Coumadin (warfarin) be given to a 30-week pregnant woman?

Coumadin at 30 Weeks Gestation

Coumadin (warfarin) can be given to a woman at 30 weeks gestation, but it must be discontinued approximately 2-3 weeks before planned delivery (around 36-38 weeks) and switched to heparin to prevent fetal intracranial hemorrhage during delivery. 1

Safety Profile in Second and Third Trimesters

At 30 weeks gestation, the patient is well past the critical first trimester period when warfarin embryopathy occurs (weeks 6-12). The key considerations at this gestational age are:

• Warfarin is relatively safe during the second and third trimesters with substantially lower fetal toxicity compared to first trimester exposure 1
• The risk of embryopathy (nasal hypoplasia, stippled epiphyses) is essentially eliminated after 12 weeks gestation 1
• CNS abnormalities can occur with warfarin exposure during any trimester, but these complications are uncommon 1
• Minor neurodevelopmental problems may occur (OR 1.7), though these are likely of minor clinical importance with no differences in mean IQ or academic performance 1

Critical Management Before Delivery

The primary concern at 30 weeks is planning for safe delivery, not current warfarin use:

• Warfarin must be discontinued and switched to UFH or LMWH approximately 3 weeks prior to planned delivery (around 36-38 weeks gestation) 1
• This timing reduces the risk of delivering an anticoagulated infant, which can lead to fetal intracranial hemorrhage during vaginal delivery 1
• If a woman goes into labor while on warfarin, appropriate reversal of anticoagulation followed by cesarean section reduces the risk of fetal intracranial hemorrhage 1

Transition Strategy at 36-38 Weeks

The recommended approach for transitioning off warfarin before delivery:

• Switch to intravenous continuous infusion UFH to maintain aPTT >2 times control levels 1
• The mother should be hospitalized before planned delivery for this transition 1
• Intravenous heparin should be stopped at least 6 hours before delivery to reduce maternal bleeding risk and allow safe epidural anesthesia placement 1
• Exact timing must be coordinated with obstetrics and anesthesia teams 1

Alternative Approach for Specific Populations

For women with mechanical heart valves requiring high-level anticoagulation:

• Some advocate for planned cesarean section at 38 weeks with only a brief (2-3 day) interruption of anticoagulant therapy 1
• This approach resulted in good neonatal and maternal outcomes in a study of 30 babies 1
• However, cesarean section carries its own risks and should be reserved for appropriate indications 1

Dose-Dependent Considerations

If the patient is on low-dose warfarin (≤5 mg/day):

• Continuation of low-dose warfarin throughout pregnancy poses the lowest combined risk to mother and fetus 1
• The rate of warfarin embryopathy is reduced to <3% (but not eliminated) with doses ≤5 mg/day 1
• Still requires transition to heparin 2-3 weeks before delivery regardless of dose 1

Common Pitfalls to Avoid

• Never allow vaginal delivery while the mother is fully anticoagulated on warfarin - this creates high risk of fetal intracranial hemorrhage 1
• Do not wait until labor begins to plan the anticoagulation transition - this should be coordinated weeks in advance 1
• Warfarin crosses the placenta and results in an anticoagulated fetus, unlike heparin preparations which do not cross the placental barrier 1
• The FDA considers warfarin contraindicated in pregnancy due to risks, but clinical guidelines recognize situations where benefits outweigh risks, particularly in the second and third trimesters for specific indications like mechanical heart valves 2, 1