The First Photos of Kate Middleton's Royal Baby Bump Are Here

The Duchess of Cambridge, Kate Middleton, has made her first public appearance since announcing that she is expecting her third child. On Tuesday, World Mental Health Day, the Duchess stepped out with Prince William and Prince Harry with their Heads Together campaign for a reception at Buckingham Palace, where they met mental health workers from across the UK.

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Kate, who covered her growing baby bump in a light blue Temperely London dress, has not been seen in public since Aug. 30, when she joined the Princes at Kensington Palace to dedicate a new garden to honor Princess Diana on the 20th anniversary of her death.

According to The Daily Mail, a royal aide confirmed on Tuesday that the Duchess is still suffering from hyperemesis gravidarum, an acute form of morning sickness she also had while pregnant with George and Charlotte, but things have been "improving." The aide added, "She is delighted to be here tonight." The condition likely caused Kate to miss 4-year-old George's first day of school at Thomas's Batersea on Sept. 8. At the time, a source told Us Weekly that Kate "watched the news from home" and "was desperately sad that she couldn't make it."

Shortly after Kensington Palace confirmed Kate's pregnancy, People reported that the Duchess was "less than three months" along, which means George and Charlotte will have a new sibling to fawn over in late spring.