Mother's Age Linked To Autism In Child

By Margarita Nahapetyan

A new data shows that delaying motherhood increases a woman's chances of having an autistic child.

In particular, a new study has found that the older a mother is when she gives birth to a child, the higher is a child's risk of having autism, and that women over 40 years are nearly 50 per cent more likely to deliver an autistic child than mothers under the age of 30.

Previous research has suggested that the risk of autism was primarily linked to the age of the father, but this new 10-year study from the United States, which examined nearly 5 million births in the 1990s, shows that the father's age has almost no impact on the child's risk of autism unless the father is older and the mother is younger than 30.

Among the findings:

• Women over the age of 40 years are 77 per cent more likely to have an autistic child than women under the age of 25 years.

• Women over the age of 40 are 51 per cent more likely to have a child with autism than women with the ages between 25 and 29 years.

• Women with the ages between 35 and 39 years are 31 per cent more likely to have an autistic child when compared to women aged between 25 and 29 years.

• Women aged between 30 and 34 years were found to be 12 per cent more likely to deliver an autistic child than women with the ages between 25 and 29 years.

• Women under the age of 25 years are 14 per cent less likely than women aged 25 to 29 to have a child with autism.

• Men who are more that 40 years old are at a double risk of having a child with autism when compared to men between 25 and 29 years, but only if the mother is under the age of 25 years.

Researcher Janie Shelton, from the University of California at Davis said that this new study challenges a current theory in autism epidemiology that identifies the father's age as a key factor in increasing the risk of having a child with autism. These new findings demonstrate that while a mother's age consistently increases the risk of having an autistic child, the father's age only contributes an increased risk when the father is older and the mother is under 30 years old. Among mothers who are over 30 years, an increase in the father's age does not appear to further contribute to the risk of autism.

Autism is a pervasive developmental disorder that causes deficits and problems with social skills and communication, and is also associated with repetitive and restricted behaviors, with onset occurring prior to age 3. Abnormal brain development in the womb is thought to trigger the disorder, which mostly affects boys. Current estimates place the incidence of autism at between one in 100 and one in 110 children in the United States.

The study is published in the February issue of the journal Autism Research.