Talleyho, I was a young lady of the 1960s in the US; what was popular then and preached to you was "zero population growth." The birth control pill became popular around 1965, but the mothers sent their girls off to college with a compact of those pills in their purse against the advice of the church. However, parents then required their daughters to go to church colleges for protection and lots of rules, while the sons could go to rough and tumble football colleges. So, there I was at a church school with what was called "contraband" in my purse; very hard to get refills that way!!
In Mexico the church is bound so tightly within the family unit; I would say that the family would think it a sin as per the church if artificial birth control was used within the family. Thus, the likely result would be many, many children which, in turn, among poorer families could perpetuate poverty because of the church's advice on birth control. When a Mexican family immigrates to the US, they bring the church and their practices with them; and, therefore, the sharp increases in the US population are the many children encouraged by the church, baptized as infants, and names entered in the church registry. No need to speak the name of the church denomination; if you know anything about Mexico, you know the name.