The Duchess of Cambridge is to meet women recovering from substance abuse at a project in London, St James's Palace has announced.
The Duchess' aides said: "The Action on Addiction programme at Hope House offers a safe, secure and comfortable place for women to recover from substance dependence and receive additional support for other compulsive disorders.
"Her Royal Highness will meet clients and staff at the 23-bed residential treatment centre."
When she visits the project on February 19, Kate will be approaching the half-way mark of her pregnancy.
At 19 weeks it would be possible for William and Kate to discover the sex of their baby.
Approaching 20 weeks, an unborn child's ears and eyes, which will be closed, are in their final position and the mother may feel movement in her stomach.
Kate's last public engagement was to the National Portrait Gallery in January where, alongside Prince William, she unveiled her first official portrait.
Kate selected Action on Addiction as one of her first patronages, alongside East Anglia's Children's Hospices, The Art Room and the National Portrait Gallery.
She also chose to become a volunteer in the Scout Association.
On Valentine's Day last year Kate travelled to an Action on Addiction project to meet recovering alcoholics at a dry bar in Liverpool.
It was one of the Duchess' first solo engagements, conducted while Prince William was working in the Falkland Islands as a search and rescue pilot.
Weeks earlier, the Duchess had privately visited the headquarters on Action on Addiction to gain an in-depth understanding of the charity's work.
The 12-24 week programme at Hope House is for women aged 18 or over who have undergone detoxification and first stage treatment.
During the programme, clients participate in daily groups and workshops where they share experiences, as well as one-to-one counselling in private therapy rooms.