The church has this to say on large families:
The church does not play the numbers game. It is not the church’s teaching that Catholics must procreate in order for the Catholic population to surpass that of other religions or cultures.
The teaching of the church has much more to say about generosity and seeing the conception and birth of a child as a blessing and a privilege. It is a participation in God’s fatherhood - the very furthest one can get from a subhuman irresponsible procreation.
In addition, ecological problems will never be solved by simply reducing the number of human beings on the planet. What is required in a change in attitude with regard to ecology and our shared responsibility for the environment.
God bless,
Ut