How exciting. It's such a special time. My only advice is follow the new mum's lead. My DDs and DIL were all different after having their babies. One needed frequent company. One appreciated more practical things, a lasagne provided, the laundry pegged out etc and the third really wanted her space but loved being taken out for coffee and cake every couple of days to get out of the house.
The only thing I did the same for all three was buy a giftbag of pretty - but very comfortable - nighties, dressing gown and slippers in favourite colours with some natural, sensitive skin moisturisers and body wash etc.
I gave them shortly pre birth so they could be used at hospital or at home as desired and they all seemed pleased. I popped some big cotton granny knickers in too as I remembered from my first experience not being adequately prepared in the undies department. I don't think any of them took offence!!