[zozbot234]

Ireland and Eastern Europe are outside the Hajnal line, and yet they're one of the biggest growth success stories. I suppose we'll get our answer soon enough as to whether it really matters. Do note however that a late marriage age for females (the key finding of the Hajnal line) implies that they have to be enabled to self-support via work, which was a key step towards modern bourgeois norms and was also inherently correlated to general prosperity.