Will and Kate with Princess Charlotte
Kate Middleton holds her newborn daughter as she departs St Mary's hospital on 2 May. The duchess is said to be raising £2m for the hospital where Prince George and Princess Charlotte were born Chris Jackson/Getty Images

Kate Middleton has given the thumbs up to a charity raising funds for a children's intensive care unit at London's St Mary Hospital, where the Duchess of Cambridge gave birth to both her children. Kate is said to be raising at least £2m.

Imperial College Healthcare Charity and charity COSMIC launched the fundraising programme named St Mary's Hospital More Smiles Appeal for the hospital early this week. The charities said Kate Middleton was "so impressed" by the care she received at the hospital she was lending her support to the appeal.

The Duchess of Cambridge gave birth to her firstborn son, Prince George in July 2013 and to her daughter, Princess Charlotte, in May this year at the Lindo wing of the hospital. Over two years into motherhood, Kate said she was delighted to be a part of the cause.

"The thought of your child in an intensive care unit is harrowing for any parent," the 33-year-old mother of two little heirs said. "The commitment to expand and transform the Children's Intensive Care Unit at St Mary's Hospital will vitally guarantee more space to treat more children and support more families."

"As someone who was so brilliantly cared for by St Mary's, I am delighted to support the Children's Intensive Care Appeal, and commend the important work of all those involved in the project,'' Kate added.

The appeal aims at raising a total £10m to create a bigger, state-of-the-art facility at the hospital. According to the charities, the intensive care unit had to turn away 233 children due to lack of enough beds.

"Every year, around 400 patients are cared for in the Children's Intensive Care Unit at St Mary's but it also turns away hundreds more critically ill children because it does not have enough beds," the organisations said. "The new unit will have 15 beds, almost doubling the current number, allowing more than 200 extra children to be cared for each year."