She attended St Anne's Secondary School in Killaloe and went on to study history and English at NUI Galway, where she was also awarded a first class honours MA in 1991 for her research on the historian Edward Hay.

She went on to complete her doctoral thesis in University College Dublin in 1999, entitled "‘Far from Few’; Professional Women in Ireland, 1880-1930".

She was would frequently return to teach at Boston College and Harvard, and from 2006 to 2008 she lectured on the history of medicine in New Zealand.

Her publications included, her seminal biography on Kathleen Lynn, "Kathleen Lynn: Irishwoman, Patriot and Doctor" (2006); "Gender and Medicine in Ireland, 1700-1950 (edited with Margaret Preston) (2012); "His Grace is Displeased: The Selected Correspondence of John Charles McQuaid, 1940-1972 (edited with Clara Cullen) (2013).

[4] In 2016 the Irish History Students' Association announced the creation of the Dr. Margaret Ó hÓgartaigh Memorial Prize For The History Of Medicine And Society for the best paper on the topics of Medicine, Gender, Education, Irishwomen, Religion, or Athletics[5]