The Bible does say children are a blessing,but in today's world it is more of a risk that they will not come to Christ,seeing that the world is more arrogant,and self exalting,than in the past,and children are more disobedient than the past,which the Bible says that children honoring their parents is the first commandment with promise,and also the last generation before Jesus comes back they will not bless their father,and will curse their mother.
In other words it is more of a risk to have children today than in years past,and why take the chance,when the chance of them coming to God are less than in the past,and will decrease as time goes on.
My niece does not go to Church,nor does she believe the Bible as far as I know,and she said she does not want children for the fact the world is crazy,and does not want them to be subject to this world.
But of course with the relaxed stance that so many people take concerning Christianity,what does it matter,all they have to do is confess Christ,if they are disobedient to parents,oh well,if they are smoking crack,and marijuana,oh well,all is well,that is if they do confess Christ,but if they do confess Christ they would have to mean it,and you know how many children only say it to please their parents,but not mean it,like when the Roman Catholic Church was persecuting people in to confession,or complying,which they were doing it only to save their skin,and children might only confess so they get their parents off their back,or to give a good show to their parents,or might be forced to go to Church,which if they do not mean it in their heart it does not count.
It is a risk that some people do not want to take.