Patrick Carroll, et al. (2001) "Abortion and Other Pregnancy Related Risk Factors in Female Breast Cancer," Pension and Population Research Institute, London.

"We believe (the incidence of breast cancer) can be better explained if abortion is recognized as a relevant risk factor alongside other pregnancy-related factors. 

"The following study assesses how the different pregnancy-related factors operate in a British context and also considers how the experience of other countries with good registration systems of relevant data, including Sweden, the Czech Republic and Finland, throw light on what has been happening in Britain....

"This present study uses comprehensive national data and is therefore free from recall, response and control selection bias which can affect case-control studies. It is the first such study of this important and contentious subject ever undertaken for this country." (Patrick Carroll, London, 2001)