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J Am Acad Child Adolesc Psychiatry. 2014 Oct;53(10):1074-81.e4. doi: 10.1016/j.jaac.2014.06.009. Epub 2014 Aug 1.

Increased risk of autism spectrum disorders at short and long interpregnancy intervals in Finland.

Author information

1
Columbia University Mailman School of Public Health, New York. Electronic address: kc2497@columbia.edu.
2
University of Turku, Turku, Finland.
3
Columbia University Mailman School of Public Health, New York.
4
University of Turku, Turku, Finland; University Hospital of Turku; College of Physicians and Surgeons of Columbia University, New York State Psychiatric Institute, New York, NY.
5
Columbia University Mailman School of Public Health, New York; College of Physicians and Surgeons of Columbia University, New York State Psychiatric Institute, New York, NY.

Abstract

OBJECTIVE:

Both short and long interpregnancy intervals (IPI) are believed to present possible adverse conditions for fetal development. Short IPI has recently been associated with increased risk of autism, but whether long IPI increases risk for autism spectrum disorders (ASD) has not been thoroughly investigated. We investigated the association between short and long IPI in a Finnish population-based study.

METHOD:

This study was conducted in the Finnish Prenatal Study of Autism, which is based in a national birth cohort. Children born in Finland in 1987 to 2005 and diagnosed with ASD by 2007 were identified through the Finnish Hospital Discharge Register. A total of 2,208 non-firstborn patients with ASD and 5,163 matched controls identified from the Finnish Medical Birth Register were included in the primary analysis. The association between IPI and ASD was determined using conditional logistic regression and adjusted for potential confounders.

RESULTS:

Relative to births with an IPI of 24 to 59 months, those with the shortest IPI (<12 months) had an increased risk of ASD (odds ratio [OR] = 1.50, 95% CI = 1.28, 1.74) in confounder-adjusted models, whereas the ORs for longer IPI births (60-119 months and ≥120 months) were 1.28 (95% CI = 1.08, 1.52) and 1.44 (95% CI = 1.12, 1.85), respectively.

CONCLUSION:

This study provides evidence that risk of ASD is increased at long as well as short IPI.

KEYWORDS:

autism; autism spectrum disorders; birth spacing; interbirth interval; interpregnancy interval

PMID:
25245351
PMCID:
PMC4174278
DOI:
10.1016/j.jaac.2014.06.009
[Indexed for MEDLINE]
Free PMC Article

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