Inter-Pregnancy Intervals and the Risk of Autism Spectrum Disorder: Results of a Population-Based Study
Maureen S Durkin1, Lindsay A DuBois, Matthew J Maenner
1Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, 789 WARF, 610 Walnut Street, Madison, WI, 53726, USA, mdurkin@wisc.edu.
Insights
Short or long intervals between pregnancies increase autism risk. This study found both short (<12 months) and long (>84 months) inter-pregnancy intervals (IPIs) were linked to a two-fold autism spectrum disorder (ASD) risk.
Area of Science:
- Reproductive epidemiology
- Neurodevelopmental disorders
- Pediatric health
Background:
- Emerging evidence suggests inter-pregnancy intervals (IPIs) may influence autism spectrum disorder (ASD) risk.
- Previous studies indicated a potential link between short IPIs and increased ASD risk in subsequent children.
Purpose of the Study:
- To investigate the association between IPI and ASD risk in a large birth cohort.
- To determine if both short and long IPIs are associated with increased risk of ASD in second-born children.
Main Methods:
- Analysis of a Wisconsin birth cohort including 31,467 second-born children.
- Assessment of ASD diagnosis at 8 years of age.
- Adjusted statistical analyses to evaluate the relationship between IPI and ASD risk.
Main Results:
- Both short (<12 months) and long (>84 months) IPIs were associated with a two-fold increased risk of ASD compared to reference intervals (24-47 months).
- The association between long IPIs and ASD risk was partially confounded by a history of previous pregnancy loss.
Conclusions:
- Inter-pregnancy intervals represent a potentially modifiable risk factor for autism spectrum disorder.
- Both very short and very long IPIs warrant consideration in future research and clinical practice regarding ASD risk assessment.
Abstract:
Recent studies have reported an increased risk of autism among second-born children conceived <12 versus >36 months after the birth of a sibling. Confirmation of this finding would point to inter-pregnancy interval (IPI) as a potentially modifiable risk factor for autism. This study evaluated the relationship between IPI and autism spectrum disorder (ASD) risk in a Wisconsin birth cohort of 31,467 second-born children, of whom 160 resided in the study area and were found to have ASD at age 8 years. In adjusted analyses, both short (<12) and long (>84 month) IPIs were associated with a two-fold risk of ASD relative to IPIs of 24-47 months (p < 0.05). The long IPI association was partially confounded by history of previous pregnancy loss.
