A major international research project has found that newborn babies in Bradford had the highest levels of a potentially toxic chemical which causes lower birth weights and smaller heads.

A diet of too many chips and crisps by mums-to-be in the city is thought to be responsible for the babies registering high levels of acrylamide, a chemical found in foods such as fried potatoes.

The international study, led by the Centre for Research in Environmental Epidemiology in Barcelona, is the first in humans to examine the association between acrylamide exposure during pregnancy and birth outcomes.

It studied the diet of 1,100 pregnant women and newborns from Denmark, England (represented by Bradford), Greece, Norway and Spain, and found intake of foods high in acrylamide during pregnancy is associated with lower birth weight and a smaller head circumference.

The difference between mothers exposed to high levels of acrylamide and those exposed to low levels may be up to 132 grams in the baby’s weight and 0.33cm in the size of the baby’s head.

Low birth weight is linked to numerous adverse health effects early or later in life such as reduced stature, increased incidence of cardiovascular disease, type two diabetes mellitus, and osteoporosis. Reduced birth head circumference has been associated with delayed neurodevelopment.

The study examined several lifestyle and social factors, including smoking, but found the reason for high levels of acrylamide observed in many women in the study was undoubtedly the diet.

The highest levels of acrylamide were found in women in Bradford and the lowest were observed in Denmark.

The 186 women who took part in Bradford were drawn from the city’s Born in Bradford project, which is tracking the health of 13,500 babies born at Bradford Royal Infirmary between 2007 and 2010.

The babies of the Bradford women had the highest levels of acrylamide in the five centres, almost twice the level of the Danish babies, with the largest source of the dietary acrylamide coming from chips.

Professor John Wright, of the Bradford Institute for Health Research, who is leading the Born in Bradford study, said: “The women were selected as a sub group from within Born in Bradford. They had to give a detailed questionnaire about their diet and the types of cooking they did and blood samples were taken from mums’ and newborns’ cord samples.

“This is important new research which demonstrates a clear link between acrylamide and the health of newborn babies. The effect of acrylamide is comparable with the well-known adverse effect of smoking on birth weight.

“Our advice for pregnant mothers is to follow a balanced diet and go easy on the crisps and chips. The results provide further evidence about the potential toxicity of acrylamide and should also encourage food manufacturers to explore methods to reduce acrylamide in their products.”