"This will be a new chapter in our lives. We've already been so fortunate for the opportunity to touch people's lives around the world — Cilla as a doctor and educator, and me through this community and philanthropy. Now we'll focus on making the world a better place for our child and the next generation," Zuckerberg wrote in a Facebook post Friday.
Chan has had three miscarriages as the couple tried to have a child "for a couple of years," Zuckerberg said. He added that Chan's current pregnancy has progressed far enough that the risk of losing the child is "very low."
"We hope that sharing our experience will give more people the same hope we felt and will help more people feel comfortable sharing their stories as well," he wrote.
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Zuckerberg did not specify when the child may be born. But he noted that both Chan and the child are "healthy."
"In our ultrasound, she even gave me a thumbs up 'like' with her hand, so I'm already convinced she takes after me," Zuckerberg wrote.
The couple has been married since 2012.