I saw something that I thought was strange today, Adele says it's pretty common. During her last tour someone requested that she sign Skyfall. It's the song she did for a James Bond movie. She told the audience to "bear with me" because she has trouble hitting low notes now.
She said that when she wrote and recorded the song her voice got lower because she was "heavily pregnant". She also said it's pretty common for women's voices to do that. I've never heard that, but them again I'm a guy. What do I know.
Here is the original video and a live performance from about a year ago. Do you hear any difference?