Facebook CEO Mark Zuckerberg and his wife Priscilla Chan have welcomed baby girl Max.

Max Zuckerberg was born last week, although her birth was only made public on December 1.

Mark Zuckerberg has made the announcement in a Facebook post, accompanied by a Facebook Notes letter to the new little lady in his life.

In the letter, Mark Zuckerberg writes that he and Priscilla Chan will donate 99% of their Facebook shares – currently about $45 billion – over the course of their lives “to join many others in improving this world for the next generation”.

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The new parents have also launched the Chan Zuckerberg Initiative, which has the broad mission of “advancing human potential” but will focus specifically on personalizing learning, curing disease, connecting people, and building strong communities.

In the letter, Mark Zuckerberg also laid out his vision for the world he hopes Max will inherit, a world in which Facebook plays an increasingly central role.

The letter covers Mark Zuckerberg’s passion for giving the world access to the Internet and the investments he and Priscilla Chan have made in education, and it paints a rosy view of a world that has felt utterly grim:

“While headlines often focus on what’s wrong, in many ways the world is getting better. Health is improving. Poverty is shrinking. Knowledge is growing. People are connecting. Technological progress in every field means your life should be dramatically better than ours today. We will do our part to make this happen, not only because we love you, but also because we have a moral responsibility to all children in the next generation.”