It depends--early on you can eat and you generally feel well... I had peanut butter and apples (high protein and long lasting nutrient dense...) I drank TONS of natural electrolyte enhanced water...bottles and bottles... honey sticks (these are sugar and keep up energy)....
In my experience, at a certain point, regardless if you can eat or not by rule, you just can't stomach any more food... I don't know anyone who eats during transition LOL...
I would say to try to eat nutrient dense meals the week of your due date and keep that up as well...you could do Odwalla drinks or protein bars...