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. 2011 Jul;22(4):469-75.
doi: 10.1097/EDE.0b013e31821d0b53.

Month of conception and risk of autism

Ousseny Zerbo  1 , Ana-Maria Iosif, Lora Delwiche, Cheryl Walker, Irva Hertz-Picciotto
Affiliations

Month of conception and risk of autism

Ousseny Zerbo et al. Epidemiology. 2011 Jul.

Abstract

Background: Studies of season of birth or season of conception can provide clues about etiology. We investigated whether certain months or seasons of conception are associated with increased risk of autism spectrum disorders, for which etiology is particularly obscure.

Methods: The study population comprises 6,604,975 children born from 1990 to 2002 in California. Autism cases (n = 19,238) were identified from 1990 through 2008 in databases of the California Department of Developmental Services, which coordinates services for people with developmental disorders. The outcome in this analysis was autism diagnosed before the child's sixth birth date. The main independent variables were month of conception and season of conception (winter, spring, summer, and fall). Multivariate logistic regression models were used to estimate odds ratios (ORs) with their 95% confidence intervals (CIs) for autism by month of conception.

Results: Children conceived in December (OR = 1.09 [95% CI = 1.02-1.17]), January (1.08 [1.00-1.17]), February (1.12 [1.04-1.20]), or March (1.16 [1.08-1.24]) had higher risk of developing autism compared with those conceived in July. Conception in the winter season (December, January, and February) was associated with a 6% (OR = 1.06, 95% CI = 1.02-1.10) increased risk compared with summer.

Conclusions: Higher risks for autism among those conceived in winter months suggest the presence of environmental causes of autism that vary by season.

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Figures

Figure 1
Figure 1
Construction of the study population based on California birth file from the period of 1990 – 2002 inclusive, merged with data from the California Department of Developmental Services for the period of 1990 – 2008.
Figure 2
Figure 2
Cumulative incidence of autism to age 5 years by calendar time of conception for children born from 1990 to 2002 in California who survived past their 1st birthday.
Figure 3
Figure 3
Cumulative incidence of autism to age 5 years by month of conception for children born from 1990 to 2002 in California who survived past their 1st birthday. The shaded areas repeat the cycle.
See this image and copyright information in PMC

Comment in

References

    1. Brown AS, Begg MD, Gravenstein S, Schaefer CA, Wyatt RJ, Bresnahan M, Babulas VP, Susser ES. Serologic evidence of prenatal influenza in the etiology of schizophrenia. Arch Gen Psychiatry. 2004;61(8):774–80. - PubMed
    1. Chess S. Autism in children with congenital rubella. J Autism Child Schizophr. 1971;1(1):33–47. - PubMed
    1. Desmond MM, Montgomery JR, Melnick JL, Cochran GG, Verniaud W. Congenital rubella encephalitis. Effects on growth and early development. Am J Dis Child. 1969;118(1):30–1. - PubMed
    1. Waldman M, Nicholson S, Adilov N, Williams J. Autism prevalence and precipitation rates in California, Oregon, and Washington counties. Arch Pediatr Adolesc Med. 2008;162(11):1026–34. - PubMed
    1. Rauh VA, Garfinkel R, Perera FP, Andrews HF, Hoepner L, Barr DB, Whitehead R, Tang D, Whyatt RW. Impact of prenatal chlorpyrifos exposure on neurodevelopment in the first 3 years of life among inner-city children. Pediatrics. 2006;118(6):e1845–59. - PMC - PubMed

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