"Meghan has so much on her plate, between being pregnant and dealing with the public backlash, and she's finding the whole situation incredibly stressful", a royal insider explained.
"Over the past year, Her Royal Highness has held meetings and conducted private visits with each of these organisations", Kensington Palace said.
A theatre spokeswoman declined to comment, while Kensington Palace would not confirm the patronage.
She will be a patron of the National Theatre, the Association of Commonwealth Universities, Smart Works and Mayhew. She has previously advocated for gender equality and improvement of women's education. "Her Royal Highness feels she can use her position to focus attention on, and make a particular difference to these organizations and, more widely, the sectors they each represent".
After 33 years, the Queen has also passed on her role as Patron the Association of Commonwealth Universities (ACU) to her granddaughter-in-law.
The Duchess is expected to carry out a public visit to the NT in the coming weeks.
The organizations were naturally delighted to have Meghan's endorsement.
In December, the Duchess invited the director of the National Theatre, Rufus Norris, to a private meeting where they discussed plans for when she is the Patron of the National Theatre.
The Duchess was particularly interested in this organisation, as she has met a number of women who have seen life-changing results from the charity.
Rumours of a royal rift between the women began swirling after news emerged that Meghan and Harry will move away from Kensington Palace to make their home 25 miles away from the Duke and Duchess of Cambridge in Windsor.
The former Suits star then helped the ladies in finding outfits for women attending their second dressing, and she also sat in on interview coaching and preparation.
Mayhew is an animal welfare charity which helps cats and dogs through community initiatives and veterinary care. The Cotswolds home is meant to act as an interim home base as they await renovations on Frogmore Cottage in Windsor, which will be their new official residence starting this spring.