I kept their very first little jar of baby food, some toys and clothes.In fact I just finished looking at my eldest sons little toy the other day, and he is 40 yrs old now! Oh and his little first pair of shoes, that had(in those days) tiny bells on them.
I have something from all of them, and they know that....Plus the handmade Christening gown I made for the boys, and it looks great even now.
It's worth a try. Go to the medical imaging centre where you had them done originally, as they should have your files. You hear about people doing this kind of thing for customers who have been in a fire.