Probably because it's a tabloid newspaper? As long as no one is 100% sure, they have every reason to tell everyone that a 13 year old kid knocked up a 15 year old mutant.
My opinion on all of this is that it is all very messed up. For one the child might not actually be the dad so this hype might just be fishing for news. Also the mother doesn't actually look up to raising a child and the child definitely will not be able to raise the child. Look at this video and the emphasis is on the financial question. http://www.youtube.com/watch?v=PvnPkGl2sf4...feature=related. I personally would like to wish them look but I do feel sorry for the parents who WILL have to take care of the child sometime soon.