In the documentary series Being Serena, Serena opened up about how she wouldn’t have been able to return to her tennis form if she continued to breastfeed. “What I’ve learned through the experience: Everybody is different, every person is different, every physical body is different,” she said. “For my body, it didn’t work. No matter how much I worked out, no matter how much I did, it didn’t work for me.” Serena ultimately ended up breastfeeding Olympia for six months. “Once I got to six months, I felt good about it. Then it was just emotionally letting go. I literally sat Olympia in my arms, I talked to her, we prayed about it. I told her, ‘Look, I’m going to stop. Mommy has to do this.’ I cried a little bit, not as much as I thought I was. She was fine.” 

Source: https://www.buzzfeed.com/jenniferabidor/celebrities-sharing-breastfeeding-stories