Parental income gradients in child and adolescent mortality: Norwegian trends over half a century

Background Child mortality declined rapidly the last century in many high-income countries. However, little is known about the socioeconomic differences in this decline, and whether these vary across causes of death. Methods We use register data including all Norwegian births between 1968 to 2010 (2.1 million), and analyse how all-cause and cause-specific child (0-[5][1]) and adolescent mortality ([6][2]-[21][3]) vary with relative parental income the year before the birth Results Child all-cause mortality decreased with increasing parental relative income within all birth cohorts. Among children aged 0-5, the socioeconomic gradient for all-cause, accidental deaths, sudden infant death syndrome and perinatal factors declined over the periode, while there was no systematic decline related to congenital malformations. Among children 6-21, the gradient did not weaken similarly, although there were indications of declines in the socioeconomic gradient related to all-cause deaths, accidents, and suicides. While the absolute differences in mortality declined over time, the relative differences remained stable. Conclusion There has been a large reduction in child mortality in all socioeconomic groups across 50 years for all-cause and most cause-specific mortality groups. However, children of parents in the lowest part of the income distribution still have an elevated mortality, and the relative differences have not always been declining. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research is funded by the Research Council of Norway (Grant number 262030 and 262700) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study has been approved by the Norwegian Regional Committees for Medical and Health Research Ethics (REC), approval number 2013/2394. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Data are not publicly available; but can be accessed through Statistics Norway and the Norwegian Institute for Public Health by permission upon relevant approvals. [1]: #ref-5 [2]: #ref-6 [3]: #ref-21