Maternal and paternal age and risk of autism spectrum disorders.
OBJECTIVE
To explore the association between maternal and paternal age and risk of autism spectrum disorders (ASDs) in offspring.


METHODS
Historical birth cohort study.


METHODS
Kaiser Permanente (KP) in Northern California.


METHODS
All singleton children born at KP from January 1, 1995, to December 31, 1999, were included in the study. We identified 593 children who had ASD diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification, code 299.0 or 299.8) recorded 2 or more times in KP outpatient databases before May 2005. These children were compared with all 132,251 remaining singleton KP births. Main Exposures Maternal and paternal age at birth of offspring.


METHODS
Relative risks (RRs) estimated from proportional hazards regression models. Risk of ASDs evaluated in relation to maternal and paternal age, adjusted for each other and for the sex, birth date, and birth order of the child, maternal and paternal educational level, and maternal and paternal race/ethnicity.


RESULTS
Risk of ASDs increased significantly with each 10-year increase in maternal age (adjusted RR, 1.31; 95% confidence interval [CI], 1.07-1.62) and paternal age (RR, 1.28; 95% CI, 1.09-1.51). Adjusted RRs for both maternal and paternal age were elevated for children with autistic disorder (maternal age: RR, 1.18; 95% CI, 0.87-1.60; paternal age: RR, 1.34; 95% CI, 1.06-1.69) and children with Asperger disorder or pervasive developmental disorder not otherwise specified (maternal age: RR, 1.45; 95% CI, 1.09-1.93; paternal age: RR, 1.24; 95% CI, 0.99-1.55). Associations with parental age were somewhat stronger for girls than for boys, although sex differences were not statistically significant.


CONCLUSIONS
Advanced maternal and paternal ages are independently associated with ASD risk.
Croen
Lisa A
LA
Division of Research, Kaiser Permanente Medical Care Program, Oakland, CA 94612, USA. Lisa.A.Croen@kp.org
Najjar
Daniel V
DV
Fireman
Bruce
B
Grether
Judith K
JK
D000293:Adolescent; D000328:Adult; D020817:Asperger Syndrome / Q000209:etiology; D001321:Autistic Disorder / Q000209:etiology*; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D010331:Paternal Age; D016016:Proportional Hazards Models; D012307:Risk Factors