78 years ago, 'Rhoda' was born
In the opening credits of season one, Rhoda tells the audience "I was born in December, 1941. I've always felt responsible for World War II".
Since December 7 was the bombing of Pearl Harbor, it seems her birthdate is December 7, 1941. (Harper was born on August 22, 1939).
There is one episode of DYNASTY, where Alexis says she was born on December 7 as well - and Blake quips there's a reason she was born when WWII started. So that would make Alexis Carrington share the same birthday as Rhoda Morgenstern - though Joan Collins was born May 23, 1933.