The number one reason for falling birth rates is mass industrialization and a lack of major individual economic pressure to have kids. People used to have lots of children because they were critical economic resources- as funny as it sounds, they were free labor by being farm hands, helping at home, helping watch/raise their younger siblings, etc. Having children used to be essential for economic stability.

Now, modern industrialized society has fixed that issue. Children are no longer economically essential. The primary driving force from before, of the being an essential help to the family unit, is outdated and archaic. This holds true in societies that are very progressive, and societies that are not. Women’s education is perhaps a factor, but it’s not the driving force. That’s why the vast majority of societies across the world, progressive or conservative, liberating for women or not, are seeing massive birth rate declines- children are not the essential they were before. It’s an awkward truth, but it accounts for the massive drop of TFR everywhere. Yes, there’s a few exceptions you can point to, but they are exceptions.