Want to increase risk of developing Schizophrenia? Keep smoking during pregnancy

A case-control study covering 15 years of births suggests mothers who smoke during pregnancy may be...

putting their children at higher risk of developing Schizophrenia.

The team of authors, from New York and Finland, believes the study was the first to examine the relationship between a maternal smoking biomarker and schizophrenia. It was published in The American Journal of Psychiatry.

• “It provides the most definitive evidence to date that smoking during pregnancy is associated with schizophrenia,” researchers wrote.
• “If replicated, these findings suggest that preventing smoking during pregnancy may decrease the incidence of schizophrenia.”

The prevalence of cigarette smoking during pregnancy in the United States and Europe is 12%–25%, according to the study.

Researchers conducted a population-based nested case-control study of all live births in Finland from 1983 to 1998. They identified 977 cases of schizophrenia in offspring from a national registry and matched them to control subjects based on date of birth, sex, and residence.

Using quantitative immunoassay, the team prospectively measured cotinine levels in mothers’ early- to mid-gestation serum specimens archived in a national biobank.

They found a higher maternal cotinine level, measured as a continuous variable, was associated with higher odds of schizophrenia in offspring. Maternal nicotine exposure defined as “heavy” was related to a 38% increased odds of schizophrenia.

Heavy smoking based on cotinine was reported by 20% of the mothers of cases, but only 15% of the mothers of control subjects, according to Columbia University’s Mailman School of Public Health, one of the organizations involved in the research.

Researchers said the findings could not be accounted for by maternal age, maternal or parental psychiatric disorders, socioeconomic status, or other covariates, and there was no clear evidence that weight for gestational age mediated the associations.

The study also involved researchers from Columbia University Medical Center and the New York State Psychiatric Institute.

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