funny enough before people used to make estimates of how earth won't have resources to carry a large population. hence some people would need to settle in space or that there needs to a massive drive in birth control, which led to Chinese 1 child policy which has had a devastating effect.
The movie even starts with news of the dead of the last human born... a 18 years-old argentinian
If you measure it in terms of sustainable human life on earth, it was rather effective
And all for supposedly controlling a birth rate that had already fallen to 2.7 by the time it was implemented. And modern scholarship suggests the typical effects of economic development would have kept it running down steadily without all the costs incurred by an unevenly enforced law, given what happened everywhere else that had no birth-control policies.
The whole world seemed to buy into the narrative at the time, but history has shown it to be an example of misguided authoritarian foot-gun akin to the Four Pests campaign.