They have their oldest kids serving missions.

I know it's not common, but really I was just trying to be funny with the stereotype. I'll put it into words:

If a wife can still have kids (i.e. under 40), she always wants one more.
If a wife is too old to have more, the number she has "is perfect."
A man always wants however many kids are not living under his roof.

I hope this doesn't offend:
women who have babies after 40
men who want more children
Divorced parents
parents who can't conceive
Men
Women
Children
people who want to adopt after 40
people who want to adopt before 40
people who put their children up for adoption
bears
beets
Battlestar Galactica
Couples who have lost a child to tragedy
Couples who have lost a child at the mall, got a call that their child was at the security desk, then used the free babysitting to have a quick date at panda express before picking up their child.
Men who enjoy having their adult children at home so they have halo partners
Women who don't want to be mothers
Women who just want to focus on their careers, but wouldn't mind adopting later on.
Men who got hit in the junk and as a result, this is a tender subject for them.
Ordain Women
Disdain Men
Dane Cook
Two cups of Flour
One Egg
Whisk Gently to combine.
The disenfranchised Polynesian community
The Enfranchised Polynesian community
People who hate long lists
Women and men who love the kids they have and have the kids they love and kid with the loves they have.
Canadians.