Jennifer Garner expecting a boy

Jennifer Garner and husband Ben Affleck are expecting a boy, according to friends.

Jennifer Garner is expecting a baby boy.

The actress and her husband Ben Affleck - who already have two daughters, Violet, five, and two-year-old Seraphina, together - are "thrilled" about their impending arrival and Boston Red Sox fan Ben, 39, can't wait to take his son to baseball games.

A friend of the couple - who announced the pregnancy in August - told Life & Style: [Ben's] thrilled at the prospect of a little sports buddy. He can't wait to take his son to baseball games and play catch with him."

However, Jennifer, 39, is said to be slightly worried about having a son after being used to daughters.

The pal added: "She feels like she won't know what to do. She's close to her two sisters, and her instincts were spot-on with the girls. But she never had a brother and doesn't know the drill."

Jennifer, 39, has previously spoken out about motherhood, saying there is no right way to raise children and she does things to suit her family.

She said: "It's tricky, I don't think there's any right way to be a mom. Whatever works for you, don't judge yourself for it. And don't let others judge you. Just do what feels best for your family, and if that's going to work, then go to work with your head held high, and if that's staying at home, then don't let yourself feel any less for being at home with your kids."