Smoking during pregnancy can increase a baby’s chances of developing schizophrenia later in life, a study has shown.

Research in Finland found that the more women were exposed to nicotine the greater chance they had of having a child affected by the severe mental illness.

Signs of heavy nicotine exposure in a mother’s blood were associated with a 38 per cent increased likelihood of schizophrenia.

Scientists analysed data on 1,000 schizophrenia patients and matched their birth and health records with those of non-affected “control” individuals.

Smoking habits were assessed by looking at levels of a nicotine marker, cotinine, in the blood.

Based on this measurement, a fifth of mothers of schizophrenia patients were found to have smoked heavily while pregnant, compared with 14.7 per cent of mothers of controls.

Nicotine is known to cross the placenta easily and enter the foetal bloodstream, leading to neurodevelopmental abnormalities

Senior researcher Alan Brown, a professor from the University of Columbia in New York City, said: “To our knowledge, this is the first biomarker-based study to show a relationship between foetal nicotine exposure and schizophrenia.”

Women participating in the study had been recruited into the Finnish Prenatal Study of Schizophrenia.

Blood tests were carried out during the first and early second trimesters (three-month periods) of pregnancy.

Nicotine is known to cross the placenta easily and enter the foetal bloodstream, leading to neurodevelopmental abnormalities. The research is published in the American Journal of Psychiatry.

Brown added: “These findings underscore the value of ongoing public health education on the potentially debilitating, and largely preventable, consequences that smoking may have on children over time.

“Future studies on maternal smoking and other environmental, genetic, and epigenetic factors, as well as animal models, should allow identification of the biological mechanisms responsible for these associations.

“Finally, it is of interest to examine maternal cotinine in relation to bipolar disorder, autism, and other psychiatric disorders.“

Previous research by the same team showed that offspring of mothers who smoked while pregnant have an increased risk of bipolar disorder.