High-income countries are experiencing both unprecedentedly low and increasingly polarized fertility with growing social gradients in childbearing. Key theories on fertility patterns are based on the empirical observation that until recently fertility remained comparatively high in gender-egalitarian countries with strong support for families. Since 2010 many of the countries that provided evidence for such theories have reached record-low fertility. This confronts the scientific paradigm of the key drivers of fertility. BIOSFER investigates how social, biological and psychological factors work together to produce the observed patterns, levels and variation in fertility among young adults, and to what extent the fertility decline and the related polarization can be attributed to social vs. biomedical factors. Our multi-theory approach leverages ideas from several disciplines and proposes that the existing theories must be complemented with concepts of risk aversion and information, intergenerational transmission of fecundity, epigenetics and beyond, in order to understand modern fertility behaviour. We develop theoretically informed, falsifiable hypotheses that we test against the two richest population-based longitudinal pregnancy and pubertal cohorts in the world, MoBa in Norway and the DNBC in Denmark. We offer a uniquely integrative life-course-based approach that is neither social or biomedical, but combines central ideas from both, and evaluates the biosocial determinants of the key transition points from fetal life through puberty and partnering into planned, unplanned, partnered and unpartnered childbearing. We study the social, biomedical and psychological forces, their interactions, and intergenerational forces as they operate throughout the life-course to produce the modern low-fertility landscape. The results will help to provide a novel, bio-social framework for understanding the life-course processes that drive contemporary fertility patterns.
We aim to untangle the drivers of today’s low and polarized fertility. Our overarching goal is to generate deeper knowledge of reproductive health and behaviour that advances scientific understanding of low fertility and is beneficial for individuals’ family planning and political resource allocation. We will characterize in unprecedented detail the present fecundity and fertility aspirations in young adults using innovative biological measures and socio-demographic data (Research Arm (RA) Present). We look into the past to early life, prenatal, and intergenerational influences to examine their potential effect on present fecundity and fertility, using stored samples, existing data, and linked registers (RA Past). We look forward to the future by following the young adults through their 20s and examining the joint role of socio-demographic circumstances and fecundity in shaping childbearing aspirations and outcomes(RA Future). We ensure synergy by design as we incorporate transdisciplinary perspectives that merge the biological and social in each of the RAs.
Our project brings together complementary yet distinct knowledge, expertise and resources in a new way. It focuses on questions of pressing importance, whose answers will have transformative scientific potential. We test an array of hypotheses that focus on fundamental questions about human reproductive health. The size, scope and duration of MoBa and the DNBC, the bold novel approaches and unique synthesis of ideas and researchers will enable testing these hypotheses in longitudinal settings that are unmatched worldwide. Our ability to study fecundity and fertility prospectively at the levels of individuals, couples and population, and potentially new biomarkers of fecundity for both women and men, will push the frontiers of fertility science. The new knowledge gained will be important for characterizing fecundity and fecundity trajectories and policies. For instance, if we find that social settings are the foremost force that drives reproductive aspirations and outcomes, it is important that resources be channelled towards modifying settings that result in unintended outcomes. If biology largely dominates, it is critical to allocate resources to eliminate offending environmental exposures that affect this biology and devise prevention modalities.
