Chau Tran

The transition to parenthood is one of the most common yet profound life events in adulthood, bringing substantial changes in identity, social relationships, daily routines, and psychological functioning. Although previous research has extensively examined how becoming a parent affects well-being, findings remain mixed. Existing studies have primarily examined a limited range of psychological well-being indicators while relying predominantly on panel studies with widely spaced assessments that are unable to capture the dynamic nature of the transition, leading to a focus on average developmental trajectories while overlooking individual differences and day-to-day fluctuations. This dissertation addresses these limitations by adopting a multidimensional perspective on psychological well-being, examining hedonic well-being, eudaimonic well-being and self-esteem, and by combining traditional longitudinal methods with intensive daily assessments. Across two complementary research streams, the dissertation investigates how expectations shape the transition to parenthood and how new mothers’ psychological well-being unfolds across pregnancy and early motherhood, with the aim of providing a more comprehensive understanding of adaptation during this important life transition.

Chapter 2 investigates whether expectations about the value of children influence both the likelihood of becoming a parent and subsequent family-life satisfaction. Using nationally representative longitudinal panel data from Germany following respondents for up to eleven years, the study examines how perceived costs and rewards of having children are associated with the transition to parenthood and adaptation thereafter. The results show that individuals with more positive prenatal expectations are more likely to become parents, and among those who do, more negative expectations are associated with lower postnatal parenting pleasure and family satisfaction. Yet, prenatal expectations do not predict the trajectory of family-life satisfaction following childbirth. These findings highlight the importance of pre-parenthood expectations for both selection into parenthood and subsequent family-life experiences.

Chapter 3 examines changes in psychological well-being across the transition to motherhood using Project NiMo, an intensive longitudinal study that followed first-time mothers from pregnancy until six months postpartum through three waves of questionnaires and daily experience sampling. Moving beyond previous research that has primarily focused on life satisfaction, this study simultaneously investigates affective, cognitive, and eudaimonic well-being while examining mean-level change, between-person differences, and within-person day-to-day fluctuations. The findings demonstrate that different dimensions of well-being follow distinct developmental trajectories and that considerable heterogeneity exists in new mothers' adaptation to parenthood. Furthermore, daily well-being fluctuates substantially throughout the transition and is associated with everyday contextual factors such as sleep, infant characteristics, and social experiences, underscoring the dynamic nature of psychological adaptation during early motherhood.

Chapter 4 focuses on the development of self-esteem and the satisfaction of the basic psychological needs for autonomy, competence, and relatedness during the transition to motherhood. Drawing on the same intensive longitudinal design, the study investigates both developmental trajectories and daily fluctuations while testing competing theoretical perspectives on the psychological foundations of self-esteem. The findings indicate that self-esteem is closely linked to basic psychological need satisfaction at both the between-person and within-person levels. In particular, perceived competence emerges as the strongest and most consistent predictor of self-esteem, suggesting that feeling capable in the parenting role is central to maintaining a positive sense of self during early motherhood.

Chapter 5 investigates how daily affective forecasts shape well-being during the transition to motherhood. The study simultaneously examines the effects of forecast valence (i.e., expecting a good or bad day) and forecast error (i.e., the discrepancy between expected and experienced affect) on daily well-being. The findings show that both more positive daily forecasts and smaller forecast errors are associated with higher daily well-being for new mothers. Exploratory analyses further indicate that forecast error is a more robust predictor of daily well-being than forecast valence, suggesting that whether experiences match or violate expectations may matter more for mothers' daily psychological functioning than simply expecting the day to be positive or negative. Moreover, the effect of forecast error is asymmetric: well-being is more strongly diminished when mothers experience a worse day than expected than it is enhanced when the day turns out better than expected. These findings demonstrate that expectations influence well-being not only in the long-term but also through the accuracy of everyday affective forecasts during early motherhood.

Taken together, the studies in this dissertation provide a comprehensive perspective on psychological well-being across the transition to parenthood by integrating long-term developmental processes with day-to-day psychological dynamics. The findings demonstrate that adaptation to parenthood cannot be understood through a single indicator of well-being or a single average developmental trajectory. Instead, different dimensions of psychological well-being develop differently across the transition, substantial individual differences exist in these trajectories, and everyday experiences contribute importantly to the process of adaptation.

By examining both existing large-scale longitudinal panel data and an intensive longitudinal study specifically designed to capture psychological experiences during pregnancy and early motherhood, this dissertation advances current understanding of how major life transitions shape new parents psychological well-being. Moreover, it shows that expectations operate across multiple timescales, from expectations formed years before becoming a parent to affective forecasts made each morning, and that these expectations play an important role in shaping both family-life satisfaction and daily psychological functioning. Together, these findings contribute to a more nuanced understanding of the transition to parenthood and provide directions for future research and interventions aimed at promoting parents' psychological well-being.