Britain's Prince William and Duchess Catherine are relieved they no longer have to keep her pregnancy a secret.

While the couple were forced to announce the news before passing the 12-week mark when Catherine was rushed to hospital earlier this month with hyperemesis gravidarum - acute morning sickness - they are happy not to have to lie to their friends and family anymore.

Catherine's friend Jessica Hay said: ''Neither Kate nor Will like keeping secrets this huge. They're relieved that everyone knows.''

Meanwhile, a friend of William's late mother Princess Diana hopes the couple name the baby after Diana if it's a girl.

Marie Sutton told In Touch Weekly magazine: ''Diana would have been a doting grandmother. She was such a lovely, basic, down-to-earth lady. She would have loved Kate. If it's a girl, the name would have to be Diana.''

Jessica recently revealed Catherine - who was known as Kate Middleton before her marriage - had ''always loved'' the name Diana.

She said: ''Catherine's been saying, as per her mother's suggestion, that she wants to meet the baby first and then decide. If it's a girl, Victoria is a favourite and, funnily enough, Diana is a name that Catherine has always loved.''