Is Kate Pregnant?

I was just talking to a friend about last week's episode, 316. She believes that it's very possible that Kate is pregnant. Here's her argument: Ms. Hawking said that the group needs to recreate the original conditions of the flight as best as possible. This includes not just the people on the plane but other seemingly trivial details like Locke wearing Christian Shepherd's shoes. Another one of these details may be that a U.S. marshal accompanies a passenger (formerly Kate, presently Sayid). Why not have a pregnant passenger as well? It's possible that Kate became pregnant when she and Jack spent their last night together before they returned to the island. How fun would that be for the Kate, Jack, and Sawyer love triangle - to have Kate carry Jack's baby. Well-played writers, well-played...