The objective of this thesis is to evaluate the similarities and differences of the childbearing motivations (CM) in a sample of adult men and women from the countries of Brazil and Peru. Specifically, the objectives were to investigate the relationships of the CM with biosociodemographic variables (ex. Sex, age, work, marital status, number of siblings, care of younger siblings in childhood or adolescence), psychological (positivity, religiosity, personality), relational (dyadic adjustment and family support) and reproductive (reproductive desires).The total sample was 4014 subjects; 2029 Peruvians (68.1 percent women) from 22 departments of the country and 1985 Brazilians (83.6 percent women) from 27 different states. Chapter I aims to describe the state of the art in the study of CM through a systematic review and two theoretical reviews that aim to describe the main theories that explain CM, the empirical evidence that supports them and the description of the model Trait - Desires-Intentions-Behaviors used as the theoretical basis of this thesis. Chapter II, composed of three psychometric articles, describes the adaptation and validity analysis of the Childbearing Motivation Questionnaire (CBQ) (Miller, 1995) for use in Brazil and Peru and tests the possibility of using this scale for cross-cultural studies in both countries. Chapter III, composed of two empirical articles, analyzes the positive (PCM) and negative (NCM) childbearing motivations for parenting in the Brazilian and Peruvian population respectively, analyzing their relationships with sociodemographic variables, related to childhood, personal characteristics and couple relationship. Finally, chapter IV, through three cross-cultural articles, provides data on the differences and similarities of PCM and predictor variables of PCM and as well as the relationship of PCM with reproductive desires in Brazil and Peru. We note the need for continuity of studies on this subject. This thesis aims to contribute to the area of reproductive psychology by providing an instrument to measure CM for use in the Peruvian and Brazilian context and by presenting results never before discussed in the Latin American literature in this field.