The press caught Middleton shopping for maternity wear in London a few weeks ago, though a roomy Zara cape mostly concealed her bump.
This time, Kate, 31, wore a relatively form-fitting Max Mara wrap dress to her official engagement at Hope House, a London rehab facility for women run by Action on Addition, for which Middleton is a patron.
"Well done for getting sober," the duchess told one woman in an art therapy class at the center, according to The Telegraph.
"You can tell a lot from people's questions and she asks really good questions," Nick Barton said. "They're not routine stuff, they're questions of someone who wants to learn. I find her very easy to deal with."
“I can only speak of what I know, and having met the Duchess several times I find her to be engaging, natural and genuinely interested in the subject," he said.
Mantel described the duchess as a "show-window mannequin" whose only purpose was to give birth in a recent lecture at the British museum.
Kate is due in July.