Okay, here's my big analysis of this whole stupid TomKatKitten ordeal. Remember when Tom jumped on Oprah's couch like a Thetan gone mad? I checked the dates, and that was May 23, 2005. The funeral in Austalia was February 17, 2006.
My guess is that Tom had just found out Katie was pregnant with his love spawn the day he appeared on Oprah, which is why he went totally bonkers. If you date the pregnancy from then, and zoom thru to the pix we saw of her while in Australia where she definitely looked pregnant, then I would say the baby was probably born shortly after returning from the Australia trip... either late February or early March. That would work out pretty well from the May 23 appearance on Oprah's show, I think.