Lionsgate has rounded out the female cast of “What To Expect When You’re Expecting” with Elizabeth Banks joining Cameron Diaz, Jennifer Lopez, Anna Kendrick and Brooklyn Decker in the motherhood comedy.

Lionsgate announced the casting Monday. Banks will portray a baby-crazy character — the author of a children’s book about breast feeding and owner of The Breast Choice boutique. She’s militant in her beliefs about what makes a good mother until she gets pregnant for the first time.

Lionsgate has selected Mother’s Day weekend next year to release “Expecting.”

The minimajor acquired feature rights to Heidi Murkoff’s bestseller from Phoenix Pictures early last year and put Kirk Jones on to direct in March. Shauna Cross (“Whip It”) penned the final draft in which the focus is on four interconnected couples.

Mike Medavoy, Arnie Messer and David Thwaites are producing, with Doug McKay co-producing, through their Phoenix Pictures banner. Heidi and Erik Murkoff will executive produce along with their literary manager Alan Nevins of Renaissance Literary & Talent.

Banks has also been cast in Lionsgate’s “The Hunger Games. She’s represented by UTA, Alissa Vradenburg of Untitled Entertainment and Ziffren Brittenham LLP.

Lionsgate also announced Monday that Rob Huebel (“The Other Guys”) has been cast in “What to Expect.” He will play a member of a motley crew of new dads who congregate in a city park in what is considered part play group, part secret society.