Actually, I think this is pretty simple. Tell them that she had unprotected sex and that sex leads to pregnancy. If they don't know this already, they SHOULD.* This is a great teachable moment to start letting them acquire the knowledge that unprotected sex leads to pregnancy. I would also tell them that her tv show is cancelled and that she has a hard road ahead of her. I would use this as an opportunity to tell my children that being pregnant at 16 is a very bad life choice.What about girls even younger, say 9 & 10 yr olds who who are fans, how do you explain to them that "Zoey" is pregnant!?
*When dd was 11 I was at her middle school and overhead a conversation between two 11 year olds in which one was saying that her boyfriend (also 11) was pressuring her to have sex and she didn't want to -- one reason being that she didn't want to get pregnant and she would since neither of them have enough money to buy condoms. Her 'friend' told her not to worry about it bec if she got pregnant her mom would just take care of it for her. They were 11.