Kate - This is an account from a note book supposedly written in 1872.
"Charles Lett was born when his mother, whose maiden name was Elizabeth Whitney, had arrived at three score years, and was suckled by his own niece, Betty, wife of William Jeffares of Furzitown. He enjoyed his mother's fostering care for forty years as she lived to upwards of 105 years and, to the last possessed such vigour of mind and body that she walked to and from her parish church on Christmas day, when she had completed her century". Of course with transcriptions there can be mistakes, but by the sound of it she was well past child bearing age when she gave birth.