Kate poised for first public appearance since pregnancy news

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The Duchess of Cambridge is hoping to make her first public appearance since news broke of her third pregnancy, at a Buckingham Palace reception recognising mental health workers.

Kate, who has been suffering severe morning sickness - hyperemesis gravidarum - has not attended an official engagement for more than a month and even missed Prince George's first day at school at the start of September.

But the Duchess has been named by Kensington Palace, alongside husband William and Prince Harry, as the royal hosts of a palace reception celebrating the contribution of those working in the mental health sector.

The evening event - being held to mark World Mental Health Day - will recognise the progress, hard work and dedication of those determined to raise awareness of mental health issues over many years.

William, Kate and Harry have supported the issue with their Heads Together mental health campaign that has been encouraging people to speak out about their psychological problems or be a sympathetic ear for others.

Kensington Palace announced on September 4 that Kate was expecting her third child and, like previous pregnancies with Prince George and Princess Charlotte, was suffering from severe morning sickness.

The Duchess is thought to be less than 12 weeks' pregnant with her bout of hyperemesis gravidarum (HG) forcing her to pull out of an event at the beginning of September which prompted the palace to make the pregnancy announcement early.

Normal morning sickness affects around 70% of pregnant women, and causes some degree of vomiting and discomfort commonly during the first trimester (12 weeks) of pregnancy.

But those suffering from HG can be constantly sick morning, noon and night and unable to keep any food or drink down.

Experts warn the condition often gets worse with subsequent pregnancies but those who have experienced it before can be put on medication as soon as they get a positive pregnancy test.

During the day William and Harry will host a reception at St James's Palace to celebrate the impact of their Heads Together campaign, and to thank all those who played a key role in its success.

Guests will include a number of the Heads Together runners who took part in the London marathon, people who shared their mental health stories in the campaign's video series, representatives from the initiative's charity partners, with the Duke and Prince delivering speeches.