The mother's microbiome -- the collection of microscopic organisms that live inside us -- can determine the risk of autism and other neurodevelopmental disorders in her children, suggests a study.

The study raises the possibility that preventing forms of autism could be as simple as an expectant mother modifying her diet or taking  custom probiotics. The findings showed that an unhealthy microbiome in the mother can make her unborn child susceptible to neurodevelopmental disorders. But, blocking a particular inflammatory molecule interleukin-17a (IL-17a) produced by the immune system can help halt the development of such disorders in lab mice.

"We determined that the microbiome is a key contributor in determining susceptibility (to autism-like disorders), so it suggests that you could target either the maternal microbiome or this inflammatory molecule IL-17a," said lead researcher John Lukens, from the University of Virginia in the US.

"You could also use this (IL-17a) as a biomarker for early diagnosis," he added, in the paper published in the Journal of Immunology. While blocking IL-17a might offer a way to prevent autism, Lukens said that the path carries much more risk. It is because blocking the molecule "could make you susceptible to all kinds of infections". And doing so during pregnancy could have complex ripple effects on a child's development that scientists would need to sort out, he said.

However, the microbiome can be modified easily, either through diet, probiotic supplements or faecal transplant. All of these approaches seek to restore a healthy equilibrium among the different microorganisms that live in the gut, the researchers noted. "In terms of translating our work to humans, I think the next big step would be to identify features of the microbiome in pregnant mothers that correlate with autism risk," Lukens said. "I think the really important thing is to figure out what kind of things can be used to modulate the microbiome in the mother as effectively and safely as we can."