I think it could be either Rick or Shane's baby. The storyline would make it more interesting, however, if it was Shane's. Don't know IF there will be a way we'd be able to tell as the story unfolds. Then again, remember Lori telling Rick and Shane "it's Rick's baby no matter what?" Maybe she really felt it was Shane's.
TIS
"Mankind must put an end to war before war puts an end to mankind. War will exist until that distant day when the conscientious objector enjoys the same reputation and prestige that the warrior does today." JFK
Don't know IF there will be a way we'd be able to tell as the story unfolds. Then again, remember Lori telling Rick and Shane "it's Rick's baby no matter what?" Maybe she really felt it was Shane's. 
