Yep, dairy cow lifespan and conditions was one of the first points that started me to becoming vegan.

I've found that many (past me included) don't really make the connection that, because cows only give milk when impregnated, dairy consumption necessitates that the number of cows multiply.

I guess, if you don't know the numbers (or don't think about it too much, since the numbers aren't that surprising), then you might think that one pregnancy is enough for years of milk production, or that the born cows would be bred for selling meat anyways.