How research on personality development can improve our understanding of perinatal adjustment

Personality plays a crucial role in mental health and adjustment to major life experiences. It affects whether individuals do or do not have children and how they deal with pregnancy and parenthood. Early research conducted more than 50 years ago primarily examined the predictive role of maternal neuroticism during and after pregnancy. More recent studies broadened their focus on the Big Five openness, conscientiousness, extraversion, agreeableness, and emotional stability (i.e. reverse neuroticism) and other personality traits. For example, there is evidence that individuals being less open to experiences are more likely to start a family (Asselmann & Specht, 2021; Denissen et al., 2019; van Scheppingen et al., 2016) and that more extraverted and emotionally stable women experience less fear of childbirth (Asselmann et al., 2021) and fewer psychopathological symptoms during the perinatal period (Asselmann et al., 2020).

Importantly, personality not only predicts but also changes due to life experiences (Denissen et al., 2019). In young adulthood, conscientiousness, agreeableness, and emotional stability tend to increase, a pattern referred to as the ‘maturity principle’ (Roberts et al., 2005). Contextual theories assume that such changes may (at least partly) result from age-graded life events (e.g. childbirth). The Social Investment Principle suggests that life events typically induce changes in social roles and role demands that require more ‘mature’ behaviour (Roberts & Wood, 2006). Because most people strive to adjust well and act accordingly, their personality might change. For instance, becoming a parent requires taking responsibility for a child, which might lead to higher levels of conscientiousness. Although frequently investigated, there is, however, surprisingly little support for this idea. Controlling for age effects, becoming a parent was mostly unrelated to Big Five changes or even linked to decreases in openness, conscientiousness, extraversion, or emotional stability, which is inconsistent with the ‘maturity principle’ (e.g. Asselmann & Specht, 2021; Denissen et al., 2019; Pusch et al., 2019; van Scheppingen et al., 2016).

How to explain these seemingly counterintuitive results? First, the birth of a child might induce changes in parents’ self-perception but less so in actual thoughts, feelings, and behaviours. Ambulatory assessment studies would be particularly helpful to test this idea. Using such approaches, (expectant) parents could regularly report their momentary thoughts and feelings in time to experience in the months around childbirth (e.g. via smartphone). In addition, objective behavioural data could be captured in daily family life (e.g. via video or audio recordings). Such data could be compared with retrospective self-reports on perceived personality changes to test for incongruencies.

Second, family life can be fulfilling but also challenging, which might induce antagonistic changes in specific facets of broader traits. For example, new parents might be more gentle (e.g. due to interactions with their infant) but also more irritable (e.g. due to lack of sleep), resulting in non-significant changes in total emotional stability. Studies with fine-grained assessments on different facets of individual traits are needed to test this assumption.

Third, becoming a parent might trigger antagonistic personality changes in different life domains. For instance, parents might become more reliable in childcare but less perfectionist at work, leading to overall stable conscientiousness. To test such hypotheses, personality must be assessed separately in different situational contexts, which is rarely the case.

Fourth, personality changes might vary between individuals and average out in the population as a whole. For example, some parents might become more but others less agreeable during pregnancy and after childbirth. Closely tied to this idea is the question of what factors explain different developmental trajectories (e.g. an increase or decrease in agreeableness). In this regard, more research is needed on the psychosocial and biological mechanisms (e.g. hormonal changes) underlying personality change, including gender differences. Such studies are predestined for transdisciplinary approaches involving researchers from psychology, medicine, sociology, and/or gender studies.

Another issue is which personality changes predict favourable or unfavourable pregnancy, birth, and infant outcomes. Prior studies mostly examined how individual differences in trait levels relate to such outcomes (e.g. higher vs. lower levels of agreeableness). In contrast, far less is known about individual differences in personality changes and their predictive power for perinatal adjustment (e.g. increasing vs. decreasing agreeableness). To illustrate, do steeper increases in extraversion promote social support in the first months postpartum? Do steeper decreases in emotional stability result in higher levels of fear of childbirth? Research on this topic promises useful starting points for early risk detection, prevention, and promotion of family health. For example, (expectant) parents with particularly fast or pronounced changes in certain traits might benefit from targeted personality interventions to ease adjustment.

Because previous research on perinatal changes typically focused on mothers additional studies on fathers/partners and interactions between both parents would be desirable (e.g. using social network and dyadic approaches like the Actor-Partner Interdependence Model). To illustrate, how do couples’ personalities influence each other? Do decreases in maternal agreeableness trigger decreases in paternal agreeableness and vice versa? How do personality changes in one partner impact the relationship, family system, and parent or infant health over time? Respective findings are highly relevant for systemic family interventions.

In sum, research on personality development can contribute to an improved understanding of perinatal adjustment. To capture long-term developmental trends and enable long-term predictions, potential changes should already be captured several years before the birth of a child. Household panel studies such as the German Socio-Economic Panel (SOEP) are predestined for those analyses: (1) They are based on large samples that include enough childless individuals who will have children in the upcoming years, so that prospective analyses are possible. (2) Panel members are repeatedly assessed over years or decades, so that continuous and discontinuous short- and long-term changes can be modelled. (3) They enrol multiple members of individual households and thus are ideally suited for family network and dyadic approaches (e.g. in couples).

Large-scale long-term panel data could be ideally complemented by intense longitudinal studies across the perinatal period: High-frequency personality measures in everyday contexts would allow examining (a) how personality states in specific situations depend on contextual factors (e.g. infant behaviour) and (b) how short-term fluctuations in momentary personality states translate into long-term changes in broader personality traits.