The statement also added that 35-year-old Duchess Kate is again suffering from hyperemesis gravidarum, better known as acute morning sickness, forcing her to cancel plans to attend an event in London on Monday morning.
This is published unedited from the PTI feed.
The news was announced as the royal couple were preparing to send their eldest child, Prince George, off to school for the first time.
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A change in law after William and Kate Wednesday gave women the same rights of accession to the throne as men. Last week the royals toured the garden of their Kensington Palace home to remember the princes' mother and celebrate her contributions to their family and to the monarchy.
The royal family is growing!
On an overseas tour to Singapore in 2012, when he was asked by a group of teenagers how many children he would like to have, he said he was "thinking about having two".
And Kate also gave an extremely telling clue that she wants more children in the future in Poland.
There were several signs that Kate could be expecting, according to reports.