I'm looking for some substantial (say >10k entries) datasets which contain birthdates which will have been user-reported, not recorded from or checked against official records.
Ideally, these would be showing data recorded before ~1950, but more recent is also interesting. Other information isn't important (though it would be helpful to know general demographic information about the sample, like "American women") and completely anonymised other than birthdate is fine, assuming there's some way to avoid duplication of entries.
For context, I'm looking at mis-reporting/mis-recall of birthdays - hence why self-reporting is important - and so far have worked with British and Canadian WWI service records. We have a fairly good idea of how this data was gathered and can be confident that the majority came through asking the person, and not by looking at ID (which few if any people carried around in this period, anyway).
At a guess, the majority of data from before the mid-20th century would be user-reported (the obvious exceptions are things like birth registrations) but I'm finding it challenging to find large, easily accessible, datasets covering this period.