Finnish women and men increasingly have their children within the context of their second rather than first co-residential partnership

  • In Finland, young adults are increasingly separating from their first co-residential partner before the couple has any children.
  • On the other hand, more people are having children in their second or subsequent co-residential union.
  • Falling fertility is tied to the way we form and maintain partnerships in young adulthood.

The decline in fertility in Finland since the early 2010s has substantive and long-term societal consequences. Challenges include population aging, where a shrinking number of working-age adults supports a growing number of older-age retirees. Therefore, the causes of fertility decline are poignant for policymakers and the academic community. One potential cause of the decline in fertility is changes in norms and behaviours regarding partnership formation.

My recent study (Andersson 2023) shows that younger cohorts are less prone to have births within their first co-residential union but increasingly have them in subsequent partnerships, i.e., after separating from the first partner.

This policy brief explains the findings, places them in the context of the scholarly study of partnership and fertility patterns, and expounds on their relevance for designing policies to both a) support family formation, including fertility, and b) support parents, families, and children in the context of low fertility (family policy).

Partnership dynamics are interlinked with childbearing

Childbearing is mainly the result of births within a couple. The forms that couple unions take and the norms about how and when to engage with or commit to such partnerships have changed drastically across the 20th century. The baby boom – the high fertility of post-war years leading to very large cohorts of people born in this period – was accompanied by very widespread and early marriage.

The subsequent decline in fertility, on the other hand, was accompanied by a substantive increase in divorce and a rise in less stable partnership forms such as non-marital cohabitation. These sweeping changes are believed to represent a host of interlinked cultural and economic developments (Cherlin 2016).

Through demographic analyses of contemporary childbearing and partnership patterns in Finland and elsewhere, we have learned much about the relationship between partnership patterns and the fertility decline. One important conclusion is that we see a decrease in childbearing within partnerships rather than a decrease in partnerships more generally (Hellstrand et al 2022).

Thus, the fertility decline in Finland is not directly caused by people forming fewer partnerships.

Results – The traditional partnership context of birth is dominant but weakening

However, the dynamics of partnerships can nevertheless affect fertility. For example, if partnerships dissolve before they lead to childbearing, the process leading to childbearing needs to be re-entered: finding, deepening, and consolidating a relationship in which one may consider forming a family with a new partner (Rahnu & Jalovaara 2023).

In a recent study, I analyzed the average number of children of individuals by the time they reach the end of their reproductive years (or otherwise defined age-related cut-off point). In the study, I calculate the share of childbearing (cohort fertility) that occurs in a particular partnership form. Among other things, I consider whether it is the first cohabiting partnership ever engaged or the second or later. Does childbearing occur with the first partner individuals move in with? Or does childbearing occur in second or higher-order cohabiting partnerships – after people have separated from their first partner?

The latter pattern is (all else equal) expected to be associated with lower levels of childbearing and later childbearing than the former scenario because the process leading up to such a partnership is more volatile because a) not all who find a first partner will find a second partner and b) it leads to postponement of childbearing, limiting the years in which the couple will be able to conceive one or multiple children.

The study results in two main findings. First, the ‘traditional’ partnership context of birth is dominant. First, among the cohorts that we can follow for their full reproductive span, around three-quarters of fertility is due to births within the first co-residential union that was entered. The popular view of a ‘hectic partnering scene’ in young adulthood is not supported from this point of view in the sense that it shows that childbearing typically occurs with the very first partner (that we cohabit with) union rather than after people have browsed through multiple (cohabiting) unions.

However, second, with each younger cohort studied, the share of children born in men and women’s first co-residential partnership decreases relative to those who have their children in their second or higher-order partnership. This cohort pattern is evident for both men and women with and without university education – two factors that often show discrepancies regarding partnership and fertility behavior.

Hence, a broad trend is confirmed: People increasingly separate from their first co-residential union before having children in this partnership. Such partnership behavior is generally believed to be associated with lower fertility rather than higher fertility.

Policy recommendations

This research supports the conclusion that falling fertility is tied to how we form and maintain partnerships in young adulthood. This particular study does not inform on the (subjective) reasons why people forego childbearing with their first co-residing partner.

However, the observed behavior is in congruence with studies on the norms, expectations, and preferences for relationships of recent cohorts (e.g., Bergström 2022). Such classes of explanations may be called cultural rather than economic, as they need not primarily be the response to economic circumstances. From a policy perspective, one may consider this a demand-driven behavior: people act in accordance with their preferences. If this is the case, it begets three considerations.

First, redistribution to parents and children need not increase childbearing because this target group has already ‘surpassed the threshold’ of finding a childbearing partner. Therefore, to the extent that fertility is driven by partnership dynamics, expanding such measures for pro-natal objectives may have a very limited effect.

Second, if specific policies are to target partnership behavior, this needs to be weighed against costs and expected efficiency. It may very well be that the patterns of placing childbearing in second or higher-order unions, rather than the first, represent the new preferred way of intimate relations in society. Public policy directed at changing such personal choices requires ethical considerations.

Moreover, evaluations of programs aimed at promoting commitment to unions (i.e., marriage) and preventing union dissolution to provide economically stable households for children and partners (Berger and Carlson 2020), indicate that it is very difficult to change such behavior.

More information

Senior researcher Linus Andersson, University of Turku (


Andersson, L. (2023). A Novel Macro Perspective on Family Dynamics: The Contribution of Partnership Contexts of Births to Cohort Fertility Rates. Population and Development Review, 49(3), 617–649.

Berger, L. M., & Carlson, M. J. (2020). Family Policy and Complex Contemporary Families: A Decade in Review and Implications for the Next Decade of Research and Policy Practice. Journal of Marriage and Family, 82(1), 478–507.

Bergström, M. (2022) The New Laws of Love. Online Dating and the Privatization of Intimacy, London, Polity Press.

Cherlin, A. J. (2016). A happy ending to a half-century of family change? Population and Development Review, 42(1), 121–129.

Hellstrand, J., Nisén, J., & Myrskylä, M. (2022). Less Partnering, Less Children, or Both? Analysis of the Drivers of First Birth Decline in Finland Since 2010. European Journal of Population, 38(2), 191–221.

Rahnu, L., & Jalovaara, M. (2023). Partnership dynamics and entry into parenthood: Comparison of Finnish birth cohorts 1969–2000. Advances in Life Course Research, 56, 100548.