What is the author's style in A Midwife's Tale: The Life of Martha Ballard, Based on Her Diary, 1785-1812 by Laurel Thatcher Ulrich?

The book has eleven chapters that focus on different parts of Martha's life and one chapter that focuses on the life of the diary. Ulrich also uses these chapters to show how women, in general, lived, worked, and created their communities. Each chapter is titled with a month and a year, but Ulrich uses times before and after the given date to explain her analysis of the diary and makes it all fit well together. The only exceptions are the introduction, which leads up to the beginning of the diary, and the epilogue, which ends the story of the diary.