Nipples after giving birth

I understand that a pregnant women develops darker nipples than what she had before she got pregnant. But I've been wondering, after they give birth to the baby do the nipples stay that dark or do they go back to the lighter color they were before the girl got pregnant?

I think it varies per woman. I don't think my nipples are all that dark (hang on I'll ask my husband lol) but I could be wrong. It's sort of like asking if you'll lose the baby weight. Some women will, some won't