It's official - baby number two on way for William and Kate
Kate Middleton, and Prince William are expecting a second child following the birth of Prince George in July last year.
Kate, 32, is suffering from hyperemesis gravidarum, or very acute morning sickness, as she did in her first pregnancy, Kensington Palace said in a statement.
She is less than 12 weeks pregnant, said a royal spokesman, who asked not to be named in line with policy.
The child will be fourth in line to the British throne.
The Duchess of Cambridge did not have the easiest pregnancy to begin with, last time around.
Palace officials chose to reveal the news that Kate was expecting when she was just a few weeks pregnant after she was admitted to hospital suffering from severe morning sickness in December 2012.
Doctors diagnosed the Duchess with hyperemesis gravidarum - a rare condition which causes severe vomiting during pregnancy and can cause dehydration, weight loss and a build-up of toxins in the blood or urine called ketosis.
Kate spent three nights in King Edward VII's Hospital in central London before being discharged.
Nicola James, trustee of the charity Pregnancy Sickness Support, said the chances were that Kate would experience the same again in her second pregnancy.
"It's highly likely that if you have had it before you will have it again and it's generally worse in subsequent pregnancies. It starts earlier and is usually more severe," Mrs James said. "But if it was treated well last time and you can get things in place, you might be all right. Some women even go as far as seeing their consultant and being put on medication as soon as they get a positive pregnancy test."
Rumours that a second royal baby might not be too far off surfaced during the Duke and Duchess of Cambridge's overseas tour to New Zealand and Australia.
When William was presented with a lace shawl for Prince George in Wellington in April, he told its creator Cynthia Read "You might have to make another one soon'', prompting the suggestion that a little brother or sister for George was on the cards.
Mrs Read revealed: "The way William said it was like he was dropping a hint, letting me in on a secret.''
But Kate was quick to quash the speculation by tasting wine at a vineyard in New Zealand soon after and telling wine-makers she was really enjoying being able to drink again after giving birth.