There's allot of variables regarding the location of Birth and how well information is documented.

My Great Grandfather was of Jewish faith and there were 2 Years of Birth (1901 & 1902) used throughout his life.

He was born just before the Birth Certificate Document was implemented in Brooklyn NYC.

This situation is not uncommon for dated information/events.

-- ~Brian D. Kerr, Esq | SSG, U.S. Army (Retired) | SSA, Brigade G1, U.S. Army (Retired) |>>Known Family Surnames (Researching): Dessler, Walk(Valk), Mahler (Maler), Paradisgarten (Paradisegarten), Tomasy (Thomashy), Gluck, Preisz (Priess), Steinhardt (Steinhart), Grossman (Grosman), Sholtz (Shultz), Kaplan, Bloom, Fischer (Fisher), Levy, Baum, Duwidewic, Meisal (Maisel)<<|>>Known Family Locations/Regions (of Surnames): Poland, Ukraine, Russia, Hungary, Lithuania<<|

There is also the small matter of difference between calendars, depending on when and where you are talking about. Someone pedantic who tried to make an adjustment could easily choose a different date (to make it the same) and might adjust by 10,11, 12 or whatever number of days. 

23 Oct 1852 in one part of the world might have been 11th October elsewhere. So what exactly is a "birthday" anyway

Apart from that as others have observed, dates in reality very often (more often than not) vary wildly, even with intelligent, educated Doctors and Lawyers. By days, months or even many years. It is often completely inexplicable. Sometimes there are reasons (making a child a different age to get a cheaper shipping ticket, change conscription requirements, get married, to incorporate another child into a family who is not really a child. 

Sometimes people just didn't care about dates (at all)

Aubrey Blumzon

UK

Hi Rebecca,

You don't say what records you have seen.  It was common for people (even some born in the U.S.) to not know their exact birthdate.  My grandfather, who came to the U.S. as a young child in 1892, wrote in his diary in 1902 that "I be on or over the age of 21."  Hence, he did not know his exact birthdate.  I've seen people whose birthdates on various records change each time, i.e different month, different day, and different year.

There are at least two questions here:  first, was there a difference between the date a birth occurred and the date it was recorded;  second, were there discrepancies between when the birth actually occurred and what date was recorded in official documents filled out by the person in question?

The answer to both is "Yes".  Example No. 1:  my maternal grandmother was born in Congress Poland on April 3, 1889 (O.S.), but the birth was not recorded until July of that year.  The very next birth record is for her sister,  who was actually born in 1885.  There are at least a half-dozen other examples in my maternal line where the recording of the birth was well after the actual fact -- in one case, a male ancestor whose birth wasn't recorded until he was 15 years of age.

Example No. 2:  all the documentation created in the US for my paternal grandfather lists his date of birth as May 30, 1878, while his entry in the Kyiv metrical book for Jewish births for that year shows it as May 23rd (O.S.).  His younger brother was born on July 6, 1880, but always reported his birth date as July 19th.

There are numerous examples where my grandmothers and grand-aunts mis-reported their ages by several years (for some reason, never older, always younger), but that's the answer to a different question.  In any event, unless you see documentary evidence of your own date of birth, you have to go on what was reported to you by others, and in a time when such things as accurate dates of birth -- not to mention other identification, such as the spelling of names -- were not a priority and (more to the point) not easily verifiable by the authorities, there was little incentive for accuracy or consistency.

Joel Novis
NOVITSKIY (Kyiv, Vasyl'kiv), OLSZTAJN (Łódź Województwo), GEYMAN/HYMAN (Ashmyany), LEVY (?), POMERANTZ (Kapyl', Navahrudak)

I don't know how common it was outside of the US except that Jews in the Pale generally didn't care about exact dates.

I can tell you that in NYC in the early 20th century it was common enough.  The example you give of registering the reporting day seems to be what happened with my father and at least one of his siblings.  My father's dates were almost a month apart.  He used the legal date which was later.   His thought was that the midwife who actually registered the birth used the date of registration.

He never had any problem with this.  Now, his name was a different issue.   My, mother, father and other relatives had incorrect names on their NYC birth certificates.  Close, but not close enough.  They were all "English" names.   Again, it probably was the mid-wife who wasn't fluent enough in English.  They did not need to change their names until years later when they needed passports.  Most got their names changed, but my mother decided it wasn't worth the effort and registered with her birth name.  She didn't need the passport that much so it wasn't a problem.

In NYC judges spent lots of time doing name changes as it required a court order.  In fact, they were recently spending lots of time making these changes as the names were still being recorded incorrectly--all those immigrants--in the 21st century. It isn't cheap and it is time consuming to do so.

Jessica  Schein
NYC

Regarding birth dates.  I wonder if the birth was recorded in temple records based on the Jewish calendar date provided by the midwife?

Shelley Mitchell, NYC

On Tue, Mar 29, 2022 at 02:14 AM, Rebecca Racer wrote:

But the document confirming his date of birth lists it as October 23.  

My guess is that since he was jewish he was not officially named until after his circumcision on his 8th day, which would make sense (October 23 would be the day after his circumcision).

What you say about naming and circumcision makes a lot of sense to me too.  In the orthodox tradition, one doesn't say what the boys name will be until it's officially announced by the father during the ceremony.
You don't say which document it is "confirming his date of birth".

My GF and his brother, about 18 months apart in age, were both registered on the day in the Tomaszow Mazovietski birth register. 

I would hesitate making sweeping general statements about "Europe".
There were major differenced in regulations and customs between different countries, and probably within them as well.
A small village in Belarus (yes that' s Europe)  did not necessarily register births the way they were registered in Vienna (Europe too...).


--
Odeda Zlotnick
Jerusalem, Israel.