Is finasteride safe for women who are pregnant or breastfeeding?

No: Finasteride is absolutely contraindicated in pregnancy due to its ability to interfere with sex organ development in the fetus. I doubt we have data in breastfeeding, as its mostly a drug used in older men. I would avoid it. I'm interested to know what the indication would be for a pregnant woman to need to use finasteride, or even to have an interest in using it.

ABSOLUTELY NOT: There re multiple package warnings advising against intake as well as exposure to Finasteride during pregnancy due to possible concerns with birth defects.