The Duchess of Cambridge had been due to travel to Malta at the weekend for her first solo overseas tour but her sickness meant she was forced to cancel, with husband William stepping in at the last minute to replace her.
While on the island, he was inundated with well wishes for his pregnant wife, who is suffering once again from hyperemesis gravidarum, which causes acute sickness in pregnancy.
He told one bystander that Kate is feeling "so so".
William also told another: "Fingers crossed she'll be better soon."
Kate, 32, suffered with the same severe sickness while pregnant with Prince George, now one. During that pregnancy she was hospitalised for three days in the early stages.
This time around, the royal is being treated at Kensington Palace by doctors, with a source telling People that she is able to move around but needs to rest frequently.
During a speech in Malta this weekend, her husband joked how sorry he was that Malta had to get him and not his wife.
"I'm sorry you've got me instead of Catherine," he said. "Catherine has asked me to say how very sorry she is that she couldn't be the one to pass on the Queen's greeting to you all."
The trip to Malta was to celebrate the country's 50th anniversary of independence.
It's just the latest engagement Kate has been forced to cancel on doctor's orders. She also pulled out of attending an event in Oxford – on the day her pregnancy was announced – and appearances at the Invictus Games, organised by her brother-in-law Prince Harry.
Kate may still visit Malta in the future. The country's President Marie Louise Colceiro Preca issued an invite for William, Kate and their baby son to return in the future – although William joked that might not be a good idea!
"Malta might not survive George," he said. "There are too many precious things around here!"
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