That's not what it says.
It says for births in 1961.
It doesn't give any "effective" date.
Therefore, when it says it applies to births that took place in 1961, THAT MEANS ALL BIRTHS THAT TOOK PLACE IN 1961.
Just when do you think the feds recorded the vital statistics for births that happened in 1961?
I'll give you a clue: From what I understand, they were boxed up by the states and shipped to the feds on microfilm.
Do you think... maybe... the beginning of 1962?
It is still not consistent with the 1961 Natality Report.
You keep saying this. Prove it, or admit you're just making stuff up.
Nonsense. The effective date is the revised date. Such a document could not be used to classify anything that occurred prior to that revised date. Nobody was going to back through eight months worth of data and reclassify it based on a new revision. The government is inefficient, yes, but not that stupid.