In the article, the author argues the problem of the ATI service to pregnant, calving and nursing with grave somatic-obstetric base, specifying the existent methods of study, and also proposing the proper vision of the methodology of different managerial and medico-social aspects investigation in relation to this contingent of sick. A special role is given to the maternal death rate and its determination. The author analyses particularly the methodological sequence of the studying in the present domain, determining the diverse methods: historical, mathematical, epidemiological, comparative, statistic, etc. The ATI studies of the National Obstetrical Centre have been aimed also on some amendments of the National C Guide of Perinatology. Is argued the creating of the CNOATI in the SCR.