[fhsm]

The ~15% infant mortality at the time was spectacular progress and yet by modern standards unbearable. Medieval would have been closer to 50%. So on this measure about a third of the way back to the Middle Ages.

https://www.ined.fr/en/everything_about_population/demograph...

[js2]

Modern rates range from 0.15% (Slovenia) to 10% (Afghanistan):

https://www.cia.gov/the-world-factbook/field/infant-mortalit...

https://en.wikipedia.org/wiki/List_of_countries_by_infant_an...