Kate Middleton, the Duchess of Cambridge, and her husband Prince William have been involved with charity causes for a long time. On their wedding day in April 2011, the couple requested the wedding guests who wanted to gift them to instead donate to charities.

Before her 30th birthday in 2012, Middleton travelled across the United Kingdom for extensive research of charities, following which she picked four. The charities she chose to take under her patronage were the Art Room, National Portrait Gallery, East Anglia's Children's Hospice, and Action on Addiction, reports said.

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The Art Room was set up in 2002, aimed to raise self-esteem, confidence and independence of children aged between five and 16, through art.

National Portrait Gallery was opened in 1896 and it features portraits of the most famous people in British history. 

East Anglia's Children's Hospice supports families and offers care for children with life-threatening conditions across Cambridgeshire, Essex, Norfolk and Suffolk. Middleton lost one of her childhood friends to cancer when he was only 20 years old. 

Action on Addiction is a charity focused on helping addicts and their children. Chief executive Nick Barton said her "support will enable us to keep the issue of addiction in the spotlight". He added: "Addiction is a consuming condition that results in a great deal of harm to individuals, families, communities and society as a whole," according to Hello! Magazine.

Middleton is also known for her adventurous spirit, and loves spending time outdoors with children from different organizations. In June 2012, she took 150 children from the Art Room charity to see a production of "The Lion, the Witch and the Wardrobe" in a circus tent on the grounds of Kensington Gardens. In that month, she also joined students from King Solomon Academy primary school — an inner-city school — for a camping excursion to Kent. She checked out the tents, taught the children how to light a campfire and told them how it was to be a real-life princess. She said it was “very nice,” adding that her husband was “very sweet” and “spoiled” her, Vanity Fair reported.

Other patronages of the Duke and Duchess of Cambridge include 100 Women in Hedge Funds Philanthropic Initiatives, Natural History Museum, The Royal Foundation of The Duke and Duchess of Cambridge and Prince Harry, Place2Be, The Scout Association, SportsAid, The 1851 Trust, and Air Training Corps, according to the official website of the Duke and Duchess of Cambridge.

Before her marriage, Middleton spent some time volunteering in Chile before starting university. In the South American country, she helped with environmental programs and was also involved with a community project for disadvantaged children.

And not only charity works, the Duchess balances her royal and parental duties along them. While attending charity events, she reportedly puts her kids off to sleep. 

Middleton went through her postpartum struggles after becoming a mother for the second time. She said: "Personally, becoming a mother has been such a rewarding and wonderful experience. However, at times it has also been a huge challenge." She added: "Even for me, who has support at home that most mothers do not. Nothing can really prepare you for the sheer, overwhelming experience of what it means to become a mother. It's full of complex emotions of joy, exhaustion, love, and worry, all mixed together."