Because an ounce of prevention now is better then a pound of flesh later in the form of crime, property damage, welfare costs, hunger, suffering, drug issues, and all the other societal ailments that result when generations of unwanted, un-cared for, fatherless children are born into communities and urban centres year after year, decade after decade.

Limit child births to women who are ready, willing and able to have them,  and you guarantee a happier, healthier, safer, better educated and generally a more robust society. One best able to "Follow Jesus' teachings" if you are of that persuasion.