You could do the bring a book for the baby instead of a card and use this poem, just substitute the name of the mother and the name of the baby.
As Jennie's due date is coming near,
We're inviting friends and family dear
To choose a favorite story that they hold
That they would like Baby Ben to be told.
Instead of a card, please let Jennie look
At your special choice of a book.
And then to Baby Ben she reads
With all the love a newborn needs.
So, please choose a fairy tale or book
And in it then your name do put.
It need not cost more than a card.
Just pick a favorite. It shouldn't be hard!
there are also a lot more story book poems from the website i have provided...
Or you can ask her what kind of theme she wants for her baby's room, whinny the pooh, precious planet, rain forest, and make all of the decorations, invitations, and thank yous for the shower the same.