Naturally, discrepancies result in changing any official record. You need to consider the original information as filed and weigh it against the "correct" information and when the amendments were requested. Most of the corrections I see where not made around the time of the event. You need to look not just at the information provided and changed, but when the changes were sought and figure out the motive.
I usually find corrections to names. This includes giving "Baby" a first and middle name. (Yes, you could have a birth certificate issued for "Baby.")
|Birth certificate for Gertrude HERZIG, born November 10, 1904 in Newark, Essex County, New Jersey.|
Copied at the New Jersey State Archives by J Lutter.
|Birth certificate correction for Gertrude HERZIG. "Gertrude" was changed to "Louise Madeline."|
Note the time of correction- almost 39 years after the event.
I see two factors in correcting birth certificates in the 1930s and 1940s. First, people could apply for a Social Security Number under the 1935 Act and may have needed a birth certificate to reflect the name under which they were employed. Second, during World War II, people needed to "prove" their American citizenship.
|Birth certificate for Marie Kenny, born "December 9, 1917" at "86 W 7th St," Bayonne, Hudson County, New Jersey.|
|Birth certificate for Peter Kenny, born "March 6, 1919" in Bayonne, Hudson County, New Jersey.|
The birth certificates for these siblings appear in order. But wait- the dates were changed! Changing the date is something I don't usually see and really makes you question the validity of any of these records. Nevertheless, on the official form, under "Items to be corrected," "Date of birth" is one of the suggestions.
|Correction to birth, 25 years later, during World War II.|
The date of birth was changed by a month.
The place of birth was also changed from house number 36 to 86; but it is 86 in the original.
|On the same date as his sister sought to amend her date of birth by a month,|
Peter Kenny also amended his- by only three days.
When you encounter official corrections to a record, you will need to cite both the original and amended information and reference the respective sources.
These documents demonstrate that even a birth certificate is not absolute proof of the event.