Men and women who wait to have babies later in life may increase their children's risk for autism

Men and women who wait to have babies later in life may increase their children's risk for autism, according to a Kaiser Permanente study featured in the April issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

The study investigated 132,844 children born at Kaiser Permanente hospitals in its Northern California region over a five-year period (1995-1999) and identified 593 children who had been diagnosed with an autism spectrum disorder (ASD).

Study results show that a mother's and father's risk of delivering a child with autism steadily increases as they get older. Women ages 40 and older showed a 30 percent increase in risk for having a child with autism (1 in 123), when compared to moms between the ages of 25 and 29 (1 in 156). Men ages 40 and older had up to a 50 percent increased risk of having a child with autism (1 in 116), when compared to their 25- to 29-year-old peers (1 in 176).

Advanced age of mothers has been associated with risk of autism in several, but not all earlier studies, according to study author Lisa A. Croen, PhD, an epidemiologist at Kaiser Permanente's Division of Research in Oakland, Calif. The role of a father's age in autism has been less frequently studied, although advanced paternal age has been associated with other adverse reproductive outcomes, including miscarriage, childhood cancers, autoimmune disorders, schizophrenia and other neuro-psychiatric disorders.

"As men age, there is an increased frequency of new mutations in the cells that go on to become sperm," said Dr. Croen. "These sporadic mutations could be related to autism risk. It is possible that non-genetic factors that are more common in older parents might also account for our findings."

For reasons not fully understood, autism is on the rise, affecting on average about one in 150 children born in the United States, according to the Centers for Disease Control and Prevention, which helped fund the study. The chronic, life-long condition affects the normal functioning of the brain, impacting development of social and communication skills.

While the cause of autism is unknown, there is strong scientific evidence that the condition is genetic. Environmental factors -- such as infections, medications and pesticides -- are also being investigated for their possible role in the cause of autism.

Children with autism are four more times likely to be male. According to the study, children with the disorder were also more likely to have older, more highly educated and white, non-Hispanic parents.

A growing number of autism cases several years ago caused Kaiser Permanente physicians and leaders from throughout Northern California to design a regional program that would best serve the needs of parents and children. Using best practices, the Regional Program for Autism Spectrum Disorders (ASD) was established in 2004 under the direction of Pilar Bernal, MD.

Today, the regional program includes a team of ASD clinical champions from all of Kaiser Permanente's pediatric psychiatry and pediatric clinics in Northern California. It also includes two regional Autism Spectrum Disorders Centers, currently located in San Jose and Rancho Cordova. A third center is being planned for the Bay Area.

Research shows that early intervention can greatly improve a child's development. Kaiser Permanente provides routine autism screening for newborns to age 2 during well-baby check-ups, allowing pediatricians to refer very young children to the regional centers who they suspect may have symptoms of autism.

Dr. Croen notes the study data suggest that advanced maternal and paternal age are independently associated with ASD risk. Age effects were found to be independent of birth year and thus not explained by the increasing age of parents that has been observed in recent years. If the relationship between parental age and autism is causal, the fraction of autism in this sample attributable to having a mother or father older than 35 years is 4 percent to 13 percent, Dr. Croen says.

Future investigations are warranted that focus on the identifications of both genetic and environmental factors that correlate with advanced parental age, Dr. Croen says.

Interviews with Dr. Croen and a full-text version of the study are available upon request.

The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well being and to improve the quality and cost-effectiveness of health care. Currently, the center's 400-plus staff is working on more than 250 epidemiological and health services research projects.

Kaiser Permanente is America's leading integrated health plan. Founded in 1945, it is a not-for-profit; group practice prepayment program headquartered in Oakland, Calif. Kaiser Permanente serves the health care needs of more than 8.6 million members in nine states and the District of Columbia. Today it encompasfses the not-for-profit Kaiser Foundation Health Plan, Inc., Kaiser Foundation Hospitals and their subsidiaries, and the for-profit Permanente Medical Groups. Nationwide, Kaiser Permanente includes approximately 156,000 technical, administrative and clerical employees and caregivers, and more than 13,000 physicians representing all specialties.