On July 31, 2015, Zuckerberg announced that he and Chan were expecting a baby girl. He said he felt confident that the risk of miscarrying was low so far into the pregnancy, after Chan had already had three miscarriages. Chan and Zuckerberg announced the birth of their daughter Maxima Chan Zuckerberg on December 1, 2015. On August 28, 2017, Chan gave birth to their second daughter, whom they named August.
On December 1, 2015, Chan and Zuckerberg posted an open Facebook letter to their newborn daughter. They pledged to transfer 99 percent of their Facebook shares, then valued at $45 billion, to the Chan Zuckerberg Initiative, which is their new limited liability company that focuses on health and education.