Older moms more likely to have child with autism
Older women are more likely to have autistic children, a new study led by researchers at the University of California at Davis, California suggests.
The study shows that a 40-year-old woman was at a 50 percent greater risk of having a child diagnosed with autism than those at the age between 25 and 29.
Additionally, every five-year increase in the mother's age was associated with an 18 percent increased risk of having a child with autism.
Janie Shelton and colleagues reported their findings in the Feb 2010 issue of the journal Autism Research.
The researchers also found the paternal age is less important than the maternal age in determining the risk of autism in children, a finding that is contradictory to early studies which claimed that the paternal age has a greater impact.
According to Shelton et al., a significantly increased risk of autism in a child was only found when the father was older and the mother was under 30 years old.
For the study, the researchers examined data on 4.9 million births and 12,159 cases of autism in California recorded between Jan 1, 1990 ad Dec. 31, 1999.
Irva Hertz-Picciotto, professor at the UC Davis MIND Institute and the study's senior author, said it remains unknown why an older parent places a child at risk for autism.
Previous studies have associated advanced maternal age with a variety of other birth-related conditions, including infertility, early fetal loss, low birth-weight, chromosomal aberrations and congenital anomalies.
Autism is a behavioral disorder which is now found in one of 120 children. The cause for the health condition like many others remains unknown.