I understand your desire for hard data, and I'll admit I doubt it's there. However it's not that much of a stretch to follow from "babies survive better when people are watching them" to "it's easier to watch a baby when there are multiple people taking care of it" to "it doesn't have to be people, necessarily" to "what if sensors could do it" to "babies live longer because sensors are watching them when humans might not be".
Completely pulling numbers out of my ass for sake of argument, for every 1000 babies that survive just fine without baby monitors, there might be one or two that didn't, because mom and dad stepped away and didn't notice the kid stop breathing. Really, people survived just fine without seat belts. We kept enough of the population to survive and even thrive as a species even in incredibly dangerous cars. But now that we have them and we recognize their value, would we go back?
Completely pulling numbers out of my ass for sake of argument, for every 1000 babies that survive just fine without baby monitors, there might be one or two that didn't, because mom and dad stepped away and didn't notice the kid stop breathing. Really, people survived just fine without seat belts. We kept enough of the population to survive and even thrive as a species even in incredibly dangerous cars. But now that we have them and we recognize their value, would we go back?