"The names of the children of Revd. Mr. Moses Fisk by Mrs. Sarah his wife entered Jany 29, 1695/6. ...
Mrs. Ann: was borne 29th. October, 1678.
Mrs. Elizabeth was born 9 Febru. 1679.
..."
Note: The births were recorded in Braintree in 1695/6, but that doesn't mean the children were born there.
Given that her sister Ann was born Oct 1678, it is assumed that Feb 1679 is Feb 1679/80.
The honorific "Mrs." (probably still pronounced "mistress") was used for unmarried girls and ladies until the early 18th century. (Information taken from the Historical Preface of the novel The Birth of Blue Satan by Patricia Wynn.)
