Is it safe to take procarbazine while pregnant or breastfeeding?

Not recommeded. This is a medication that has some clear issues, especially early in pregnancy and with breast feeding. It can cause abnormalities of the feet, kidneys and the heart if you take it in the first 14 weeks. If you are on this medication, you should talk to your doctor before you get pregnant about coming off. In the second or third trimester, you should talk about if the benefits outweight risks.
Not recommended. Procarbazine is not recommended during pregnancy because there have been reports of fetal damage. It is not studied in large trials, but still is not recommended. Check with your oncologist.