Cohort profile: the Alma cohort of Swedish children born 2018-2023 - a prospective, register-based resource to study social determinants of health and Swedish child health services.

purposeSocial inequalities in child health persist even in high-income welfare states with universal child health services, yet large-scale longitudinal resources capturing early life exposures, family context and service delivery during the preschool years remain scarce. The Alma cohort was established to identify risk and protective factors for children's health and development during the first 5 years of life, with a particular focus on social determinants of health and the delivery and impact of proportionate universalism within the Swedish child health services.

participantsThe Alma cohort is a population-based register cohort comprising all children born in Sweden between 2018 and 2023, together with their parents and siblings, totalling 2 169 423 unique individuals. Of these, 690 589 are index persons (children). Individual-level data are linked across multiple national registers using the unique Swedish personal identity number, including the Total Population Register, the Medical Birth Register, the National Patient Register, the Prescribed Drug Register, the Swedish Child Health Services Register (BHVQ), sociodemographic registers, registers on out-of-home placements and the Cause of Death Register. The cohort captures substantial variation in perinatal characteristics, family structure, socioeconomic conditions and geographical context. Data are retrieved in three waves up to 2030 to enable longitudinal follow-up from birth into school age. FINDINGS TO DATE: The cohort is broadly representative of Swedish children and families. Among index persons, 51.4% are boys and 48.6% are girls. Approximately 40% have at least one parent born outside Sweden, 63.5% have at least one parent with a college or university education and 78.0% reside in urban areas during their first year of life. The BHVQ subcohort, covering 458 724 index persons from 13 Swedish regions, provides data on child health and development and service delivery within the child health services. Several studies are currently ongoing, addressing topics such as language screening, enhanced support from child health services, parental mental disorders, out-of-home care and the consequences of parental loss. FUTURE PLANS: Planned data extractions will extend follow-up through early school age, including linkage to the National School Register for data on school performance. The cohort is open to collaboration with researchers interested in child health, service evaluation and policy-relevant analyses.