If you go one page back on that url to:

<http://www.hsph.harvard.edu/healthliteracy/literature.html>

You'll find an Annual Review article that includes information on the 
Grosse and Auffrey article.

In their review, Grosse and Auffrey found that a mother's level of 
education is the strongest predictor of a child's health in third world 
countries, stronger than income or access. A group of researchers led by 
Robert LeVine explored this relationship and found that it was, in fact, 
the literacy skill level of mothers, not their years of education that was 
the predictor. In addition, they found that the mother's complexity of oral 
language was related to both the literacy skill level and the positive 
health outcomes. They have developed the theory that as mothers develop 
literacy skills, they learn to speak and understand language that is more 
academic in nature. That is, language in which the speaker provides all the 
necessary context for the listener. This is the language used by the public 
health and medical personnel who are charged with helping mothers take care 
of their health and the health of their children. The work of LeVine and 
his colleagues makes the case that there is something universal about 
literacy skill, that it helps people make sense of the whole world, not 
just the written word. This kind of research can only be done in third 
world countries where people might never have been to school or dropped out 
in the first few grades for reasons unrelated to cognitive abilities or 
family background. There might have been no school or it might have been 
too far away to allow young girls to walk to it unescorted.

John Comings, Director
National Center for the Study of Adult Learning and Literacy
Harvard Graduate School of Education
7 Appian Way
Cambridge MA 02138
(617) 496-0516, voice
(617) 495-4811, fax
(617) 335-9839, mobile
john_comings at harvard.edu
http://ncsall.gse.harvard.edu