Katherine Kallinis, left, with sister Sophie LaMontagne of “DC Cupcakes.” (TLC)

Katherine, who married D.C. lawyer Ben Berman last year, discovered she was pregnant while filming this summer. “It wasn’t really planned this way,” she told us Monday.

Nonetheless, the storyline was quickly incorporated into the show: She and sister Sophie surprised their mom — on camera, natch — with the news; a “gender reveal” baby shower is set for an hour-long special later this season.

The big news rolled out Monday morning with a story by People and a visibly pregnant Katherine on “Today” touting their new book “Sweet Celebrations” (also out Tuesday.) The baby, a first for the couple and the show, is due February.

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