AIR pollution has been shown to increase the chances of women giving birth to small babies and suffering the condition pre-eclampsia.

Professor Tanja Pless-Mulloli, who led the UK arm of the study at Newcastle University, said: "As air pollution increases we can see that more babies are smaller at birth which in turn puts them at risk of poor health later in life."

The research was published in the journal Environmental Health Perspectives at the same time as the British Medical Journal released evidence that one in every 20 cases of pre-eclampsia, when women become seriously unwell with high blood pressure, was linked to another air pollutant.

Researchers in Sweden found a link between higher ozone levels in the first three months of pregnancy and the risk of premature birth and pre-eclampsia.

Mothers with asthma were particularly affected.