Yep, Lisa Marie Presley is indeed pregnant again. She felt that she had to reveal her pregnancy because the paparazzi/medias were ridiculed by saying that she was getting heavier, so and on.
Here's the story that confirms her pregnancy and why she had to reveal her pregnancy.
I wouldn't say it a bad decision from Lisa because she got every right to keep her personal life private. So, we all know that the media can be very very vicious personal attacks when they like to pose their nose in famous people life. I mean everybody got a right to privacy then having the media and the paparazzi people causing lot of chaos and stress. I believe she did the best she could to avoid them. But it bound to happen anyway.
I think she need to not tell media not their business if she pregnant. It would be she wrote in her myspace blog to tell fans then it will eventually get to the press in no time.