Researchers have developed a novel blood test for pregnant mothers that can, with nearly 90 per cent accuracy rate, predict the probability of having a child that will be diagnosed with autism.

According to studies, if a mother has previously had a child with autism, the risk of having a second child with the developmental disorder is approximately 18.7 per cent, whereas the risk in the general population is approximately 1.7 per cent.

In the study, led by Juergen Hahn, Professor at Rensselaer Polytechnic Institute in New York, metabolites of the folate-dependent transmethylation and transsulfuration biochemical pathways of pregnant mothers were measured to determine whether or not the risk of having a child with autism could be predicted by her metabolic profile. 

Pregnant mothers who have had a child with autism before were separated into two groups based on the diagnosis of their child whether the child had autism or not. Then these mothers were compared to a group of control mothers who have not had a child with autism before.

The results, appearing in the journal Research in Autism Spectrum Disorders, showed that while it is not possible to determine during a pregnancy if a child will be diagnosed with autism by age 3, they did find that differences in the plasma metabolites are indicative of the relative risk (18.7 per cent vs 1.7 per cent) for having a child with autism.

"These are exciting results as they hint at differences in some metabolic processes that potentially play a role in increasing the risk of having a child with autism," Hahn said. "However, it would be highly desirable if a prediction based upon physiological measurements could be made to determine which risk group a prospective mother falls into," Hahn noted.