London, Nov 26 (IANS): Children of women who reported domestic violence during pregnancy or the first six years of the child's life are almost 50 per cent more likely to have low IQ (intelligence quotient), researchers have found.

The study, published in the journal Wellcome Open Research, revealed that only 13 per cent children whose mothers didn't experience domestic violence had IQ below 90 at 8 years of age.

Low IQ is defined as an IQ score less than 90. Normal IQ is considered to be 100.

If mothers experienced physical violence from partners either in pregnancy or during the first six years of the child's life, the figure rises to 22.8 per cent, according to the researchers from the University of Manchester, the UK.

The study examined the link between domestic violence -- also called intimate partner violence (IPV) -- and child intelligence at 8 years, using 3,997 mother-child pairs from The University of Bristol's Avon Longitudinal Study of Parents and Children.

"We know one in four women aged 16 and over in England and Wales will experience domestic violence in their lifetime and that their children are at greater risk of physical, social and behavioural problems," said lead author of the study Kathryn Abel from University of Manchester.

"We also know intelligence in childhood is strongly linked with doing well in adulthood, though there has been little evidence about the risk of low IQ for these children," Abel said.

"While we can't conclude that IPV causes low IQ, these findings demonstrate domestic violence has a measurable link, by mid-childhood, independent of other risk factors for low IQ," Abel said.

The study follows children from pregnancy, and measures emotional and physical domestic violence from pregnancy until eight years of age. The intelligence of the children was measured at eight years using the Weschler Standardised IQ test.

This study shows the chance of a low IQ rises to 34.6 per cent if the mother was repeatedly exposed to domestic violence.

That means children with mothers who repeatedly suffer domestic violence during pregnancy and the first six years of their child's life are almost three times more likely to have a low IQ at 8 years of age, researchers found.

According to the researchers, 17.6 per cent of the mothers in the study reported emotional violence and 6.8 per cent reported physical violence.