I'm not christian, but I do have a scientific idea of the afterlife. I have heard about OBE's (out of body experiences) and its truly amazing. The one seven year died for about 45 minutes yet to her she was fully conscious and dettached from her body. The emergency doctors measured the brain activity (as is required) of the girl and, as you would expect of a dead person, there was absolutly no brain activity. That would mean that, because she and thousands of others claim was conscious, that there must have been brain activity outside of the brain. What does this have to do with heaven you may ask. Well, it could be that (I personally haven't completely accepted this, but) when you die, all that happens id that your neorons and all your brain activity happens outside your body and you are basically bodilies, floating information. You may ask, how can there be outside brain activity if there is nothing to connect the information. Well, I personally think that the answer lies in an experiment that has been done. What happened in this experiment was that there were two atoms that were completly alike in every way that were seperated by about a mile. Then another atom had its information but into the other atom so that the atom changed into the other form. Here's the fascinating part, The other atom, a mile away, changed its form into the other atoms form. The information seemed to instantiously be transfered to the other atom a mile away. Maybe that is information would be communicated outside the brain, maybe not, the afterlife by no means has been scientifically proven to exist and even if it were we defianently haven't figured out scientifically. In a more direct answer to your question, a fetus (assuming fetuses are conscious in there mother womb) would remain unconscious, a child would maintain its intellegence and possibly gain wisdom (in other more scientific terms-collect more data of its environment) after in died and samegoes for adults.