The research was done to explore how much does transition theory supports findings of pregnancy and post-delivery experiences and to obtain a contribution from data to theory . Purpose: To identify the characteristic elements of transitions in pregnancy and post-delivery by means of transition theory. Specific aims: 1) to understand women's experience during the transition from pregnancy to post-delivery; 2) to explore woman's abilities and resources to face changes; 3) to set forth pregnancy and post-delivery transition conditions that lead to a healthy transition. Methodology: In the year 2004, a research of a case study was conducted. One case was pregnancy transitions and the another was the post-delivery one. Participant women ente red the study in pregnancy week number 26 and remained as such until post-delivery week number 8. There were implemented instruments to assess risk, depressive symptomatology, life Quality and social support. Home visit and in-depth interview were used. Findings: Transition nature, conditions and indicators were identified. News about pregnancy and lactation are critical moments. Partner's participation is highly valuable; planning, real expectations and previous experience contribute to a healthy transition. Conclusions: Transitions theory contributes with elements to guide caring. There was literal and theoretic replication, as well as an additional element for the theory: the spiritual dimension. Recommendations: To involve the partner and to support the woman when facing news about pregnancy and lactation, as well as to prize the spiritual dimension and to research about it.