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Children born to women who reported domestic violence in pregnancy or during the first six years of the child’s life are almost 50% more likely to have a low IQ at age 8, according to a study on a British population, published in Wellcome Open Research. We discuss the associated negative influence this can have on the children’s later life outcomes and what can be done to help mitigate the adverse effects.

1 in 4 women age 16 and over in England and Wales will experience domestic violence in their lifetime. This is not only harmful to the mothers but could impact her children too, as researchers found that children born to mothers with physically violent partners are more likely to have a lower IQ than children born to mothers who do not experience domestic violence. This could negatively influence the children’s later life outcomes because intelligence in childhood is strongly linked with them doing well in adulthood.

This is the largest study to examine the extent of intimate partner violence, which includes emotional and physical domestic violence, on mothers and the link with children’s cognitive development. The research from University of Manchester, led by Dr Kathryn Abel, found that 13% of children whose mothers did not experience domestic violence had an IQ of below 90 at 8 years of age (an IQ score of 100 is considered to be a normal IQ, while an IQ score les than 90 is defined as a low IQ score).

If their mothers experienced physical violence from their partner either in pregnancy or during the first six years of the child’s life, the figure rises to 22.8%. If the mother was repeatedly exposed to domestic violence the chance of a low IQ rises to 34.6%. Therefore, 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.

Kathryn Abel says: “While we cannot conclude that intimate partner violence causes low IQ, these findings demonstrate domestic violence has a measurable link, by mid-childhood, independent of other risk factors for low IQ.”

Nearly one fifth of mothers reported violence by their partner from the start of the pregnancy up to around six years after the birth of their child, with 17.6% reporting emotional violence and 6.8% reporting physical violence. Most physical violence occurred between the birth of the child and during the first 6 years after the birth, which was negatively associated with the IQ of eight-year-old children. However, there was no association between the mother’s exposure to emotional violence and her child’s IQ.

Corresponding author, Hein Heuvelman, from University of Bristol, added: “Exposure to domestic violence is common for children in the UK and an important and often overlooked risk factor in their life chances. So, knowing the extent to which these already vulnerable children are further affected is a powerful argument for more, better and earlier intervention. Current support for women experiencing domestic violence is inadequate in some areas and absent in others. Early intervention with these families protects children from harm, but it may also prioritise their future development.”

This finding expands on previous reports, with the Office for National Statistics in 2014 estimating that 24% of women aged 16 and over in England and Wales had, at some point, been exposed to violence by their intimate partners. Roughly 30% of intimate partner violence may start, or increase in severity, during pregnancy.

The researchers assessed 3,153 mother-child pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), a population-based cohort of 14,000 pregnancies in three former Avon health districts. The intelligence of the children was measured at eight years using the Weschler standardised IQ test. The mothers completed postal questionnaires at 18 weeks gestation and then at 2, 8, 21, 33, 47, 61 and 73 months after the birth of their child about whether they had experienced emotional or physical cruelty by a partner to identify the type and the timing of exposure during the pregnancy and motherhood. The findings are independent of other risk factors for low IQ, such as, alcohol and tobacco use in pregnancy, maternal depression, low maternal education and financial hardship around the child’s birth.

Compared with mothers who reported nonviolent partners, mother exposed to physical violence were more likely to have non-white or mixed ethnic backgrounds, came from less favourable socio-economic profile, and were more likely to smoke or drink during the pregnancy. They were at greater risk of perinatal and postnatal depression and were more likely to have children with below average IQ.

Find out more about this research and read the peer review reports on domestic violence, its associated negative influence on later life outcomes and the ALSPAC study cohort on Wellcome Open Research. All quotes featured in this blog were taken from the press release by University of Manchester.