Robyn posted a video of a gender-reveal stunt from the couple's home on her Instagram account. Their two daughters, Charlotte and Bernadette, stood next to a closed box in the yard before Hayward helped them open the box. Multiple pink balloons flew out of the box, revealing that the couple was having a third girl.
"Whoa it's a girl," Hayward said.
"Is daddy happy?" Robyn asked.
"Daddy is always happy," Hayward responded.
Robyn wrote in her Instagram caption that the baby is due in January and was unplanned.
Bernadette is 3 years old. Charlotte is 2 years old. Hayward, 28, had two points and played five minutes in his only start this season for the Celtics, before going down to a gruesome fractured tibia and a dislocated ankle injury in the Celtics' season-opening loss to the Cleveland Cavaliers.
Hayward resumed basketball activities in early July for the first time since a surgery in May. He signed a 4-year, $128 million contract with the Celtics last summer in free agency.
"Once I get started, I'll be jogging, then running, and then cutting and moving, and all that could happen within one to two weeks of each other, to where by the end of July I am playing full court, five-on-five basketball," Hayward wrote in his blog on June 26. "And that's probably the most exciting thing I could tell all of you."
The 2016 All-Star averaged 21.9 points, 5.4 rebounds and 3.5 assists in his last full season.