Ancestry UK shows incorrect birth date

[Hearnoevilspeaknoevil]

Hello
Doing a bit of research into my family, using Ancestry,.
A couple of relatives born late 1970s show their birthday as being a couple of months earlier than their actual date of birth. E. G August 1979 instead of October.
This is in the summary results page.
Any ideas as to why?
Thank you.

It’ll be because they’re taking the information from quarterly indexes.

Is it the first month of the quarter they were born in?

OK thank you. That explains it i think.

Although the quarterly indexes are under the LAST month of the quarter, not the first...

Have you definitely got the right people and not someone with the same name?

if you were born in December 1968 you may not be registered until January 1969, therefore your birth registration would appear in 1969 and not 1968 (you have 42 days to register a birth)

Its an index of both registration not birthdays, and as above pp states its a quarterly list at this time