Since 1945, the number of automobiles has increased greatly and I am sure you can find some positive correlation with infant mortality, at least in some states during some time periods. But it would be a mistake to attribute an increase in infant mortality to the increase in automobiles. You have no more evidence to support your theory than I would have if I claimed that the increase in the number of automobiles was the cause. I am not sure how much text this board will handle at once, so I will stop here and post a continuation. You are afraid of all stove lids, hot or cold.
All data sets have uncertainty.
You might want to read it.