The brunette royal, who is expecting her second baby with Prince William next April, will attend a gala dinner for Action on Addiction, at which comedian Rory Bremner is performing.
The Duchess, née Kate Middleton, will attend a gala dinner on Thursday evening
The dinner will take place at L'Anima, a swanky Italian restaurant, which isn't far from the couple's home in Kensington Palace, making it especially manageable.
Her debilitating morning sickness seems to be under control and aides are considering each appointment on a case by case basis.
Looking radiant, healthy and typically chic, Kate didn't put a designer-shoe clad foot wrong at Tuesday's evening do at the Natural History Museum. She wore a new pale blue Jenny Packham creation and Prada heels for the occasion.
Tuesday was the first time Kate has been seen since the baby news
Earlier in the day, she was also seen chatting easily with Singapore's President Tony Tan and his wife at the start of their state visit to Britain.
Since announcing the pregnancy in September, the Duchess has been completely out of the limelight. She was forced to pull out of her trip representing the Queen at the anniversary celebrations for Malta's independence and several other causes close to her heart.
However, she is nothing if not a trooper and seems to have rallied enough to get back to business at what is thought to be the 13-week stage of the pregnancy.