The actress and makeup magnate, 38, was spotted Wednesday wearing a loose-fitting tee and jeans during a pre-Thanksgiving shopping trip to Bristol Farms in Los Angeles.
Also in view was Barrymore's diamond sparkler from husband Will Kopelman, who she married last year.
The pair are already parents to 14-month-old Olive, and Barrymore said she was thrilled to discover she was pregnant again.
"When I found out, I was overjoyed. It always feels so surreal, it's incredible. [I'm feeling] incredible, that 'Here we go again' feeling. And blessed. Blessed!" she said.
"Will is just thrilled – we both are – [because] we just wanted so badly for Olive to have a sibling," she says. "In some ways, it's really for her. So congratulations, Olive!"