While handing out symbolic shamrocks to members of the Irish Guards at the annual St. Patrick's Day ceremony in Aldershot, Kate revealed that while she'd like to have a boy, Prince William would prefer a girl.
As she met members of the regiment of which William, 30, is ceremonial colonel, she said she was ready to be a mom but is undecided on a name for the couple's baby.
Sergeant Thomas Laven, who was receiving a long service medal, told her he has a 7-month-old son, Theo. "I congratulated her on the impending birth and said you've got sleepless nights to come," he told reporters.
"She said she was prepared for it," he added
Inside the Mons Barracks, Kate, 31, and William posed for photographs, where the Duchess spoke with guardsman Lee Wheeler.
"I asked her do you know if it's a girl or a boy and she said not yet," Wheeler, 29, said. "She said 'I'd like to have a boy and William would like a girl.' I asked her if she had any names and she said no."
Another guardsman, Jason Perry, said, "I wished her congratulations and said I hope all is fine and well. She said yes it is."
"I asked is she excited to have her first child and she said very," Perry, 33, added.
Despite her growing baby bump, Kate fit into an outfit she wore a year ago – a green Emilia Wickstead coat to which she added a gold shamrock pin.
As she handed out sprigs of shamrock at the St. Patrick's Day parade on Sunday, she was not flustered by the driving rain and winds. But in a brief, unscripted moment, she caught one if her heels in a drain and appeared to need steadying by William.
Last year, Kate carried out the event solo because William was serving in the Falkland Islands.