Optimal interpregnancy interval in autism spectrum disorder: A multi‐national study of a modifiable risk factor
Year: 2021
Type: article
Study design: Observational Study
Abstract: It is biologically plausible that risk of autism spectrum disorder (ASD) is elevated by both short and long interpregnancy intervals (IPI). We conducted a retrospective cohort study of singleton, non-nulliparous live births, 1998-2007 in Denmark, Finland, and Sweden (N = 925,523 births). Optimal IPI was defined as the IPI at which minimum risk was observed. Generalized additive models were used to estimate relative risks (RR) of ASD and 95% Confidence Intervals (CI). Population impact fractions (PIF) for ASD were estimated under scenarios for shifts in the IPI distribution. We observed that the association between ASD (N = 9302) and IPI was U-shaped for all countries. ASD risk was lowest (optimal IPI) at 35 months for all countries combined, and at 30, 33, and 39 months in Denmark, Finland, and Sweden, respectively. Fully adjusted RRs at IPIs of 6, 12, and 60 months were 1.41 (95% CI: 1.08, 1.85), 1.26 (95% CI: 1.02, 1.56), and 1.24 (95% CI: 0.98, 1.58) compared to an IPI of 35 months. Under the most conservative scenario PIFs ranged from 5% (95% CI: 1%-8%) in Denmark to 9% (95% CI: 6%-12%) in Sweden. The minimum ASD risk followed IPIs of 30-39 months across three countries. These results reflect both direct IPI effects and other, closely related social and biological pathways. If our results reflect biologically causal effects, increasing optimal IPIs and reducing their indications, such as unintended pregnancy and delayed age at first pregnancy has the potential to prevent a salient proportion of ASD cases. LAY SUMMARY: Waiting 35 months to conceive again after giving birth resulted in the least risk of autism. Shorter and longer intervals resulted in risks that were up to 50% and 85% higher, respectively. About 5% to 9% of autism cases might be avoided by optimizing birth spacing.
Source: Autism Research
DOI: 10.1002/aur.2599
Institutions: Norwegian Institute of Public Health, Curtin University, The Kids Research Institute Australia, The University of Western Australia, University of Turku, Karolinska Institutet, Finnish Institute for Health and Welfare, Aarhus University, Kupat Holim Meuchedet, University of Haifa, University of California, Los Angeles, University of San Francisco, Icahn School of Medicine at Mount Sinai, Lundbeck Foundation, Drexel University
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Funders: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Lundbeckfonden, Norges Forskningsråd, National Institutes of Health, National Health and Medical Research Council, National Institute of Neurological Disorders and Stroke, National Institute of Environmental Health Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development
Awards: Child disability:understanding determinants and improving outcomes, G2014461362, G3987400284, Multigenerational FamIlial and Environmental Risk for Autism (MINERvA) Network, Risk of infections and chronic immune-mediated diseases among children conceived by assisted reproductive technologies, Targeted approaches to address avoidable perinatal mortality and morbidity, Evidence-based recommendations for interpregnancy intervals in high-income countries, G953547211
OpenAlex ID: W3193980868