Click to see all the stars at the Butterfly Ball
The X Factor winner, 36, looked lovely as she posed for the cameras at the Caudwell Butterfly Ball at London's Grosvenor House alongside her husband Craig.
Sam chose a floor-length black gown that fit snugly over her blossoming tummy, teamed with a black clutch bag and red lipstick. Her husband of 11 years looked dapper in a tuxedo.
Sam and Craig - parents to Brooke, eight, and five-year-old Tommy - announced they were expecting their third child together in March; the following month the star revealed they are having a baby girl.
The annual Butterfly Ball is held to raise money for disabled children and their families.
This year's gala was hosted by Peter Andre, with a special stage show from Kylie Minogue, who entertained guests by performing a number of her singles.
Host Peter Andre and Emily MacDonagh
A host of British stars headed out to show their support, including new mums Emily MacDonagh and Tamara Ecclestone, Petra Ecclestone, Emeli Sande, Holly Candy and Rachel Stevens.
Simon Cowell also attended the gala - and placed a winning bid of £100,000 on a Salvador Dali painting at the charity auction, the Mail reports.