New Baby

I got a brand new niece yesterday. She's now 1 day old and looks like a baby (though a very cute one). Welcome to the world, little one! Behave well and cry not a lot.

She's my second niece/nephew - is there a word for that? If I myself had two children, one of each gender, I could say I have "two children" rather than "one son and one daughter". Can I do a similar thing with niece/nephews? I suspect there's a very obvious word that I've forgotten due to being stupid.