Tobacco smoking during pregnancy is related to many effects on health and reproduction, in addition to the general health effects of tobacco. A number of studies have shown that tobacco use is a significant factor in miscarriages among pregnant smokers, and that it contributes to a number of other threats to the health of the fetus. Now, a study led by researchers at Columbia University identifies an association between smoking during pregnancy and increased risk for schizophrenia in children. The team state that, to their knowledge, this is the first biomarker-based study to show a relationship between fetal nicotine exposure and schizophrenia. The study is published in the American Journal of Psychiatry.
Previous studies show that smoking tobacco during pregnancy is a major public health problem leading to adverse health outcomes and neurodevelopmental abnormalities among offspring. Its prevalence in the United States and Europe is 12%–25%. Smoking during pregnancy is known to contribute to significant problems in utero and following birth, including low birth weight and attentional difficulties. Nicotine readily crosses the placenta into the fetal bloodstream, specifically targets fetal brain development, causing short- and long-term changes in cognition, and potentially contributes to other neurodevelopmental abnormalities. The current study examined the relationship between prenatal nicotine exposure, via cotinine level, in archived maternal sera and schizophrenia in offspring from a national birth cohort.
The current study evaluated nearly 1,000 cases of schizophrenia and matched controls among offspring born in Finland from 1983-1998 who were ascertained from the country’s national registry. Sera was drawn during the first and early second trimesters. Results show that heavy smoking based on cotinine, a reliable marker of nicotine in maternal sera, was reported by 20% of the mothers of cases and 14.7% of the mothers of controls.
Data findings show that a higher maternal nicotine level in the mother’s blood was associated with an increased risk of schizophrenia among their offspring, with heavy maternal nicotine exposure associated with a 38% increased odds of schizophrenia. The findings persisted after adjusting for important confounding factors including maternal and parental psychiatric history, socioeconomic status, and maternal age.
The researchers note that it is also of interest to examine maternal cotinine in relation to bipolar disorder, autism, and other psychiatric disorders. They go on to add that in a previous study from a different birth cohort, results show that offspring of mothers who reported smoking during pregnancy have an increased risk of bipolar disorder.
The team surmise that their findings underscore the value of ongoing public health education on the potentially debilitating, and largely preventable, consequences that smoking has on children over time. For the future, the researchers state that 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.