The Church already teaches that if a couple discerns serious reasons not to convceive, they may accomplish that via refraining from sexual intimacy during the woman’s fertile time.
I have three kids over 12 years of which ZERO were a surprise to us. People seem unable to believe it, but humans are mammals and mammals make recognizable symptoms of fertility. The practice is a bit harder than that, but the priniple is that easy.
Demographers have long recognized that human populations in poor rural populations grow slowly because while people get pregnant often, there is high mortality rates among both the mothers and babies. They’ve also noted that mature wealthy and urban populations (even before modern contraception) have ALSO had very low population growth rates since urban economics punishes large families. Where high population growth occurs is pretty much ONLY in societies in transition between poor and/or rural to wealthy and urban.
What contraception has done has been to artificially depress wealthy/urban fertility rates to below replacement and has also significantly speeded up the transition time to that level. Promoting contraception to prevent ‘overpopulation’ is like using a carcinogen to suppress teenage acne. Stupid, short-sighted and fatal (culturally for contraception) in the long run. The Church won’t ever promote it.