Then I filled the box with long ribbons with tags tied to them that I wrote a number of weeks on. I did them in about 2 week increments, so as she grows she can tie them around her belly and cut off the excess and keep them in her box to measure her growth. I also put some little note card so she could write down anything special about a paticular time in her pregnancy she wanted to remember. You could put little photo albums or whatever else you wanted in there, too.
And, depending on how close you were to the mother and how far she is in the pregnancy... you could write a letter to the baby and put it in there and tell about how wonderful the mother to be has been in taking care of the new baby during pregnancy, or if there were any funny stories from the pregnancy that the mother to be might not write down that you thought would be endearing for the baby to read one day. Anyways Hope you like it!