The incidence of death close to birth, is potentially associated with the biological and demographic characteristics of the mother during her reproductive history. In order to analyze the above aspects, the present article has the general objective of assessing whether some of the bio - demographic factors that will be considered here, are conditions for the occurrence of infant mortality and / or the rest of the presents infants under 5 years. To carry out this work the demographic method of life table was used , with which survival curves were obtained , taking as a source of information for this National Survey of Demographic Dynamics 2009, Mexico, allowing empirical support the results that were reached , such as: the order of birth of the child is seen as a differential to the mortality of children under 5 years , also the age of the mother is an important condition for this problem to exert greater influence on the orders first and second births in the same direction due date establishes a significant difference in the survival of children which seems to suggest a certain cohort effect, while pre- order pregnancies considered live birth has not been shown to be a variable differentiating the survival of children under 5 years. Finally it was noted that the immigration status comes as a great weight differential in infant and preschool mortality primarily in the lower orders of births.

Keywords: Infant and preschool mortality, bio-demographic conditioning, reproductive history of the mother, Baja California, Mexico