Banning the pill alone would be sufficient.[0] And you don't even need to ban it entirely, just slightly limiting the supply would be enough. Banning it entirely would double the fertility rate because the pill had cut it in half from 1960-1975 when it was introduced in the US.[1]

[0] https://en.wikipedia.org/wiki/Combined_oral_contraceptive_pi...

[1] https://www.macrotrends.net/global-metrics/countries/usa/uni...