Jennifer Garner and Ben Affleck Welcome Son Samuel

Jennifer Garner and Ben Affleck are proud parents for the third time.

The couple welcomed a son, Samuel, on Monday in Santa Monica, PEOPLE confirms. The new addition joins big sisters Seraphina, 3, and Violet, 6.

“We are happy to announce on February 27, Jennifer gave birth to a healthy baby boy, Samuel Garner Affleck,” the actor posted on his Facebook timeline.

The couple announced they were expecting in August, with Garner telling Jay Leno in January that they knew the sex of the baby, but weren’t sharing.

“It would be so weird to have a boy,” the actress told Ellen DeGeneres, but also said the experience would be “cool and different.”

Affleck, in turn, said in 2010 that the three-against-one female-to-male ratio in his house leaves him significantly outnumbered.

In January, Garner and Affleck, both 39, were photographed walking arm-in-arm, with the actress sporting a sizable baby bump.

“He knows when to swoop in with the gesture. He’s sweet that way,” Garner says of her husband. “Honestly, I would do anything for that man, because I know it’s not taken for granted.”