The Hollywood actress, who already has a one-year-old daughter Olive, seemed to be hiding a baby bump beneath a floor-length gown when she attended the LACMA Art+Film gala event at the weekend.
Charlie's Angel star Drew has made no secret of her desire to expand her family with art consultant Will Kopelman, who she married in June 2012.
"I was an only child and it was lonely," she has said. "Some people love it and thrive on the independence, but I want my kids to have other kids around."
Drew dotes on daughter Olive, who was born in September 2012. "She's a sweet person, which is all I care about," she said. "I am obsessed with nice. That's the most important thing."
Drew had a turbulent childhood, in which she spent time in rehab for drug and alcohol abuse. She once described her relationship with her mother Jaid as "my greatest battle".
She has revealed that she looks to Will's mother Coco Kopelman for inspiration.
"She's the best," said Drew. "My mother-in-law is actually my muse, just on how to be a person and a wife and a mother."