Yes, NATIVITY is a Scrabble word!

Letter values in Scrabble US: N 1, A 1, T 1, I 1, V 4, I 1, T 1, Y 4.

Is it a valid word?

NATIVITY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the event of being born
the theological doctrine that Jesus Christ had no human father; Christians believe that Jesus's birth fulfilled Old Testament prophecies and was attended by miracles; the Nativity is celebrated at Christmas

Also: virgin birth.