Prince William has wryly joked the name of "morning sickness" should be changed to reflect the fact his pregnant wife has been suffering night and day.
The Duke of Cambridge went solo at a homeless charity gala on Saturday night as Catherine rested after three days of treatment for acute morning sickness.
William did not make any reference to the apparent suicide of nurse Jacintha Saldanha, 46, who fell for a hoax call that was made to the private hospital where the duchess was being treated.
As he chatted to guests at London's Royal Albert Hall for his first public engagement since the pregnancy was announced, the duke was congratulated on the happy news.
Michael O'Higgens, former chairman of the charity Centrepoint, said William joked that the name of Catherine's illness should be changed.
"He said they shouldn't call it morning sickness as it's a day and all night sickness," O'Higgens said.
William told guests that some of the "most inspiring moments of my life" had been with the young people of Centrepoint, of which he is a patron.
He recalled spending a night on the streets in 2009 to experience what it was like sleeping rough.
"I was cold but safe, and I knew I had a home waiting for me," he said.
"Many others have no such luck. The cold streets are the only reality they know.
"And yet so often their spirit shines through.
"What these unfortunate men, women and young people could achieve given the right opportunities is limitless, I really believe that."
Guests were also treated to a tennis match between former British number one Tim Henman and Croatian Goran Ivanisevic.
The game was won by Henman, with showman Ivanisevic clowning around throughout the match.
The event ended with William presenting the Centrepoint Great Britain Youth Inspiration Award to Novak Djokovic.
The world number one, who is a UNICEF ambassador, was recognised for his humanitarian work to raise awareness of the importance of early childhood education in his home country of Serbia.