The Duchess of Cambridge has made her first public appearance since the due date of her and Prince William's third child was announced.

The royal couple are expecting the baby in April and today they were joined by Prince Harry at London Stadium for an apprentice graduation.

Kensington Palace has released pictures of all three of them talking to Coach Core apprentices about gymnastics, tennis and rugby.

Coach Core, founded by The Royal Foundation in 2012 is a legacy of the London 2012 Olympic Games and today marked five years since it was launched.

The Duchess of Cambridge hid her baby bump with a double-breasted blue coat (
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Twitter)
Rugby duty was left to Prince William (
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Twitter)
The Queen is delighted at the news of the third baby (
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Twitter)

But Pregnant Kate left the rugby playing to her husband and instead spoke with tennis coach Judy Murray and apprentices, aged between 16 and 24, who were due for graduation.

The exact due date of the baby's arrival has not been revealed and the baby will be fifth-in-line to the British throne, pushing uncle Prince Harry into sixth place.

The soon-to-be parents of three chat with someone involved with Coach Core (
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Twitter)
Prince Harry also attended the event (
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Twitter)
The former soldier will soon be an uncle for the third time (
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Twitter)

The Duchess has been suffering from hyperemesis gravidarum - a severe form of morning sickness - but made an appearance at the engagement today.

It was her third appearance since news broke that she was pregnant.

She is also due to visit Norway and Sweden with the Duke on an official visit early in 2018.

Kate showed off her growing bump (
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WENN)
The Duchess of Cambridge attended a reception on World Mental Health Day at Buckingham Palace (
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PA)
Kate Middleton joked she and Prince William 'need more babies' seven weeks before her baby announcement (
Image:
PA)

The trip was originally scheduled for next month, but has been delayed because of Kate's sickness.

The new royal baby should arrive the month before the Cambridges' daughter Princess Charlotte turns three.

Prince Williams with some of the Coach Core apprentices (
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Twitter)
Kate speaks with Judy Murray, mother of tennis ace Andy (
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Twitter)
The event was at the London Stadium (
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Twitter)

But Kate is believed to have gone beyond her due date with both Prince George and his sister.

The Duchess gave birth to George and Charlotte at the private Lindo Wing at St Mary's Hospital in Paddington, central London, and will be expected to do the same, unless she opts for a home birth.

It is likely Kate has now had her 12 week scan and seen an ultrasound image of her baby.