Outcome-dependent associations between short interpregnancy interval and offspring psychological and educational problems: a population-based quasi-experimental studyShow others and affiliations
2018 (English)In: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685, Vol. 47, no 4, p. 1159-1168Article in journal (Refereed) Published
Abstract [en]
Background: Causal interpretation of associations between short interpregnancy interval (the duration from the preceeding birth to the conception of the next-born index child) and the offspring's psychological and educational problems may be influenced by a failure to account for unmeasured confounding.
Methods: Using population-based Swedish data from 1973-2009, we estimated the association between interpregnancy interval and outcomes [autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), severe mental illness, suicide attempt, criminality, substance-use problem and failing grades] while controlling for measured covariates. We then used cousin comparisons, post-birth intervals (the interval between the second-and third-born siblings to predict second-born outcomes) and sibling comparisons to assess the influence of unmeasured confounding. We included an exploratory analysis of long interpregnancy interval.
Results: Interpregnancy intervals of 0-5 and 6-11 months were associated with higher odds of outcomes in cohort analyses. Magnitudes of association were attenuated following adjustment for measured covariates. Associations were eliminated for ADHD, severe mental illness and failing grades, but maintained magnitude for ASD, suicide attempt, criminality and substance-use problem in cousin comparisons. Post-birth interpregnancy interval and sibling comparisons suggested some familial confounding. Associations did not persist across models of long interpregnancy interval.
Conclusions: Attenuation of the association in cousin comparisons and comparable post-birth interval associations suggests that familial genetic or environmental confounding accounts for a majority of the association for ADHD, severe mental illness and failing grades. Modest associations appear independently of covariates for ASD, suicide attempt, criminality and substance-use problem. Post-birth analyses and sibling comparisons, however, show some confounding in these associations.
Place, publisher, year, edition, pages
Oxford University Press, 2018. Vol. 47, no 4, p. 1159-1168
Keywords [en]
pregnancy interval, birth spacing, psychopathology, case-comparison studies, interpregnancy interval
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
URN: urn:nbn:se:oru:diva-69100DOI: 10.1093/ije/dyy042ISI: 000444559900026PubMedID: 29566153Scopus ID: 2-s2.0-85055347510OAI: oai:DiVA.org:oru-69100DiVA, id: diva2:1252239
Funder
Forte, Swedish Research Council for Health, Working Life and Welfare
Note
Funding Agencies:
National Institute of Child Health and Development HD061817
National Institute of Mental Health T32MH094011 T32MH103213
Indiana University Mabel LaDuke Lauder Fund
National Science Foundation Graduate Research Fellowship 1342962
Swedish Initiative for Research on Microdata in the Social and Medical Sciences (SIMSAM) 340-2013-5867 350-2012-340
2018-10-012018-10-012023-12-08Bibliographically approved