I guess this is one of the things that makes us a more "advanced" culture. My experience in the third world makes me say it would be a rare church service where not one mother could be found nursing a baby at some time during the service. In fact, I know of one time when the baby in question at a baptism got hungry and the priest baptized the baby while the baby was nursing.
And to Lamont: Cry rooms are not universal either.
I grew up in small rural, declining population areas and the sound of a baby crying in church would be a welcome sign. It's not all bad.