As it is your daughter's girlfriend, I assume this is going to be your grand child? I do think the decision can be different depending on the relationship with the couple. If you want to bring something, bring something small. A pair of baby socks or similar size. I wouldn't go all out for something expensive or personalized.
These discussions remind me of the episode of Sex and the City, where Carrie has to go to a baby shower. She has to take off her shoes at the door, and someone takes her very expensive Manolo Blahniks. She wants the host to refund her the money. The host thinks it's stupid to spend so much money on shoes and doesn't want to refund the full amount
Quote: Over the years, I have bought Kyra an engagement gift, a wedding gift, then there was the trip to Maine for the wedding, three baby gifts. In total, I have spent over 23,000 dollars celebrating her choices.
It ends with Carrie sending the host a message that she is getting married to herself and is registered at Manolo Blahnik.
It can get out of hand quickly ;-)