For what it's worth (and obviously it's just a single informal anecdote), there was a song my wife and I sang quite a bit while she was 6-9 months pregnant. It

For what it's worth (and obviously it's just a single informal anecdote), there was a song my wife and I sang quite a bit while she was 6-9 months pregnant. It was pure magic after he was born -- singing it could reliably make him instantly stop crying during the first year of his life. Admittedly I don't remember when the first time we tried singing it to him after he was born, it probably was at least a couple of weeks. And yes, singing other songs generally did not have that effect.