Kate and William: morning sickness could mean twins Prince William was at his wife's side as it news came out that the royal couple are expecting. Mother-to-be Kate is to spend the next few days in a London hospital as she is suffering from a very acute form of morning sickness that sometimes indicates twins. As the news spread British Prime Minister David Cameron was among the first to congratulate the the Duke and Duchess of Cambridge. "I am delighted for them," he said. I am sure they'll make absolutely brilliant parents and I am sure everybody around the country will be celebrating with them tonight. It has not yet been announced when the baby is due, but the Prince's office said the pregnancy is less than 12-weeks along. The couple married last April and speculation about a pregnancy has been rife ever since. When the baby is born it will be third-in-line to the throne. Last year Britain and other commonwealth countries that have the Queen as monarch, agreed to change the rules of royal succession so boys no longer have precedence over girls as heir to the throne. More about: Kate Middleton, Prince William of Wales, Royal families, United Kingdom