Could be less infections. As that raises...but can also be more bacterials..as that lowers...

in 1800 we had more infections I guess... More women died too during labor... kids too died more often...

But lower temperature can also be bacterials... or more sepsis, that could be interesting as since 2007 pneumonia raised... https://www.thuisarts.nl/sepsis/ik-heb-sepsis

I think it has a cause, and or in less illness or another type... We should research it...