Sarita, a 30 year old woman develops a deep vein thrombosis in her left calf on fourth post operative day following cesarean section done for fetal distress. The patient is started on heparin and is scheduled to begin a 6 weeks course of warfarin therapy.The patient is a devoted mother who wants to breast feed her baby.What is the advice which is given to the patient:

**Core Concept**
Warfarin, a vitamin K antagonist, is contraindicated in lactating women due to its potential to cause warfarin embryopathy or bleeding in the infant. Heparin, on the other hand, is a safe alternative for anticoagulation during breastfeeding.

**Why the Correct Answer is Right**
Heparin does not cross the placenta and has a minimal effect on the fetus, making it a preferred choice for pregnant and breastfeeding women. Warfarin, however, can cause warfarin embryopathy, characterized by nasal hypoplasia and stippled epiphyses, in the fetus. Additionally, warfarin can cause bleeding in the infant, especially in cases of warfarin overdose. Heparin, being a larger molecule, does not cross the placenta or reach significant concentrations in breast milk, making it a safer choice for lactating women.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as warfarin is not a safe choice for lactating women due to its potential to cause warfarin embryopathy or bleeding in the infant.

**Option B:** This option is incorrect as there is no evidence to suggest that heparin causes thrombocytopenia in the infant.

**Option C:** This option is incorrect as there is no evidence to suggest that aspirin is a safe alternative for anticoagulation during breastfeeding.

**Option D:** This option is incorrect as warfarin is not a safe choice for lactating women due to its potential to cause warfarin embryopathy or bleeding in the infant.

**Clinical Pearl / High-Yield Fact**
Lactating women on anticoagulation therapy should be advised to express and discard any breast milk for 24 hours after the administration of heparin or low molecular weight heparin (LMWH), as these medications may be present in small concentrations in breast milk.

**Correct Answer:** C.

✓ Correct Answer: D. Warfarin is not a contraindication for lactation.