Prince William, Kate's 2nd child due in April

The second child of Prince William and his wife Kate is scheduled to be born in April, his office announced on Monday.

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William, grandson of Queen Elizabeth and second-in-line to the throne, announced last month that Kate was expecting a second baby to join Prince George who was born in July last year, but no date for the birth was disclosed at the time.

The statement from William's office also confirmed that Kate, the Duchess of Cambridge, is still suffering from Hyperemesis Gravidarum, acute morning sickness which causes severe nausea and vomiting and requires supplementary hydration and nutrients.

The condition has caused her to cancel a number of official engagements.

During her first pregnancy, Kate was so ill she required hospitalization. This time, she is being treated by doctors at her residence in Kensington Palace. She cancelled a planned engagement in Oxford to rest and receive medical care.

Prince William told well-wishers in Oxford in September that Kate should be over the worst of her symptoms in a few weeks.

"She wishes she could be here," he said.

"She's feeling OK, thanks. It's been a tricky few days — week or so — but obviously we're basically thrilled, it's great news, and early days. We're hoping things settle down and she feels a bit better."

The new baby, boy or girl, will become fourth in line to the throne, pushing Prince Harry to fifth. George is third and likely to become Britain's monarch one day. William is second in line, while his father, Prince Charles, is first.

Britain had changed its laws before George's birth so that the couple's first born would be in line for the throne regardless of its sex. Before the change, a girl would have lost her place in line if a boy was born later.

William and Kate have often expressed an interest in having a larger family.