Kate Middleton and Prince William
Kate Middleton and Prince William will welcome their second child in April Getty

Kate Middleton is reportedly still struggling with her antenatal sickness.

The Duchess of Cambridge, who is pregnant with her second child, has been suffering from hyperemesis gravidarum, a potentially serious pregnancy illness causing vomiting and a bodily reaction to the intake of food and liquids.

"Kate's starting to feel really pregnant. She's been joking about never passing up an opportunity to use the loo!" a family friend told Us Weekly.

However the 32-year-old royal, who is already mother to Prince George, is slowly recovering and is preparing for the new baby.

"Now that things are settled health-wise, she's loving being surrounded by her girlfriends, having a laugh and talking baby things," the friend added.

The Duke and Duchess of Cambridge, who will welcome their second child in April, are planning to have a communal children's playroom at their Norfolk mansion.

"But George won't have to share his bedroom. I'm not sure George understands that Kate is pregnant. But they are talking to him about having a new brother or sister. They're making sure he's prepared the best they can," the source added.

Meanwhile, royal biographer Andrew Morton had previously revealed that the couple will name their second child Diana, if it's a girl.

"Close friends to William and Kate have told me that if it is a girl they want to name the baby after Diana. They discussed girls' names before George was born and now they're hoping the next one is a girl so they can carry out their wish to honour William's mother.

"They're not too thrilled at the thought it will be shortened to Princess Di. But it won't change their minds," Morton told The Sun.