back in the day of old, I wore cloth diapers but mothers today don't know what cloth diapers are, all they know is disposable diapers, so as Doc commented, diapers are always a welcome gift. don't forget the wipes.
do away with disposable diapers...they fill up land fill and never rot. buy cloth diapers, lots of them and offer to wash them for her when needed. offer to babysit so she can rest or go out. make a meal she can freeze. tell her...if you need anything just ask. is it her first or? ????. if it her first shell need help.
A gift certificate to a nice day spa escape where she can relax and indulge in a facial, mani/pedi and or a massage. She would really appreciated. If you volunteer to watch the baby while she goes to the spa, she'll love you forever! :)
something for her. right now its all about the new baby and she's probably jot feeling too much like a woman anymore. babysitting is always a good one, so she can either sleep or get out of the house or even take a shower. maybe help with some chores she got behind on because babies are very time consuming, a gift certificate for a coffee shop or some store she likes, maybe some bath beads or something that will melt away the stress.