Source: Bang Showbiz NewsCelebrities have taken to twitter to congratulate Prince William and Duchess Catherine on their baby news.The Duke and Duchess of Cambridge announced on Monday (03.12.12) they are expecting their first child together and stars including Cheryl Cole and Maria Shriver have sent their congratulations to the couple.Cheryl - who has previously admitted to a crush on William's brother Prince Harry - wrote: "I'm sooooooo excited that we're having a royal baby !!!! Congratulations to Kate and Wills !!!!!! (sic)".Meanwhile, after it was revealed Catherine - who was known as Kate Middleton before her April 2011 marriage - has been admitted to hospital with Hyperemesis Gravidarum [severe morning sickness], Maria revealed she once suffered from the same illness.She tweeted: "Wonderful news for Prince William & Kate Middleton. Kate has Hyperemesis. Had that with my last child. Not fun at all. Hang in there, Kate."Other stars to tweet their congratulations include Olly Murs, who wrote: "Cool #royalbaby that's amazing news!! Dam it how comes they never mentioned it on the XTRA Factor last week haha (sic)," while Katherine Jenkins added: "What lovely news!! Congratulations to the Duke & Duchess of Cambridge!! #PitterPatter (sic)."The duchess is believed to be less than 12 weeks along but the news was announced early as she was admitted to the King Edward VII Hospital in Central London to deal with her illness.Prince Harry - who is currently serving in Afghanistan - was informed of the news via email, while Queen Elizabeth and Prince Philip only found out on Monday before the announcement.