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. 2009 Sep;99(9):1673-9.
doi: 10.2105/AJPH.2008.149021. Epub 2009 Jul 16.

Estimated autism risk and older reproductive age

Marissa D King  1 , Christine Fountain, Diana Dakhlallah, Peter S Bearman
Affiliations

Estimated autism risk and older reproductive age

Marissa D King et al. Am J Public Health. 2009 Sep.

Abstract

Objectives: We sought to estimate the risk for autism associated with maternal and paternal age across successive birth cohorts.

Methods: We linked birth records and autism diagnostic records from the California Department of Developmental Services for children born in California between 1992 and 2000 to calculate the risk associated with maternal and paternal age for each birth cohort as well as for the pooled data.

Results: The categorical risks associated with maternal age over 40 years ranged from a high of 1.84 (95% confidence interval [CI] = 1.37, 2.47) to a low of 1.27 (95% CI = 0.95, 1.69). The risk associated with paternal age ranged from 1.29 (95% CI = 1.03, 1.6) to 1.71 (95% CI = 1.41, 2.08).

Conclusions: Pooling data across multiple birth cohorts inflates the risk associated with paternal age. Analyses that do not suffer from problems produced by pooling across birth cohorts demonstrated that advanced maternal age, rather than paternal age, may pose greater risk. Future research examining parental age as a risk factor must be careful to avoid the paradoxes that can arise from pooling data, particularly during periods of social demographic change.

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Figures

FIGURE 1
FIGURE 1
Percentage of the population over 40 years of age at child's birth by gender, California, 1992–2000.
FIGURE 2
FIGURE 2
The observed prevalence of autism in the total population and in populations born to a mother or father over 40 years of age, California, 1992–2000.
FIGURE 3
FIGURE 3
Compared with age 30 years or younger, the relative risk for autism, by birth cohort, associated with (a) maternal age 40 years and older and (b) paternal age 40 years and older: California, 1992–2000.
FIGURE 4
FIGURE 4
The effect of cumulatively pooling data across additional birth cohorts on the measured risk associated with maternal or paternal age, California, 1992–2000.
FIGURE 5
FIGURE 5
Effects of maternal and paternal age obtained from the decomposition equation, California, 1992–2000. Note. The coefficient represents the increased odds of autism resulting from the unique contribution of maternal and paternal age.
See this image and copyright information in PMC

Comment in

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