Children born to mothers who are severely overweight have a higher chance of developing conditions such as ADHD, scientists have found.

Researchers said public health strategies to help women planning pregnancies reach and maintain a healthy weight could address the risk.

Recognising severe obesity as a risk factor could also lead to the development of prevention strategies, they said.

The results were produced by a team from the universities of Edinburgh, Glasgow and Helsinki in Finland.

Previous studies have shown that babies born to obese mothers face a greater risk of developmental issues, such as attention deficit hyperactive disorders (ADHD) and neurodevelopmental problems like autism.

Scientists looked at the likely impact on children born to mothers classed as severely obese, with a body mass index (BMI) of 40 or above.

They studied symptoms of mental disorders linked to the nervous system in 112 children aged three to five, who were born to obese mothers.

Those youngsters born to severely obese women had a "significantly higher likelihood" of hyperactivity, sleep problems and conduct issues, the study concluded. They were also more likely to suffer problems such as anxiety, depression and aggressive behaviour.

Researchers said the results suggest the risks are higher for children of severely obese mothers and could mean maternal weight is a strong indicator for whether children are likely to develop brain-related psychiatric disorders.

The risk remained higher even when other factors were taken into account, such as the mother's mental health, social status and whether she smoked.

Professor Rebecca Reynolds, of the University of Edinburgh's Centre for Cardiovascular Science and Tommy's Centre for Maternal and Fetal Health, said: "This research underlines the importance of finding ways of helping women plan for pregnancy by optimising their health, including reaching and maintaining a healthy weight."

The findings are published in the journal Psychological Medicine and the research was funded by the charity Tommy's.