Researchers say preventing smoking during pregnancy could reduce schizophrenia incidence.
According to the Centers for Disease Control and Prevention (CDC), in 2011, around 10 percent of women in the United States reported smoking in the last 3 months of pregnancy, despite the health risks it poses for mother and child.
Expectant mothers who smoke are more likely to have a miscarriage and placental problems, and babies born to mothers who smoke during pregnancy are at greater risk of preterm birth, low birth weight, birth defects, such as cleft lip or cleft palate, and sudden infant death syndrome (SIDS).
Increasingly, studies are suggesting that tobacco use in pregnancy may also pose risks for a child's mental health. One study published in 2013, for example, identified a link between smoking during pregnancy and increased risk of bipolar disorder in offspring.
Now, a new study from the same team - including senior author Dr. Alan Brown of the Mailman School of Public Health at Columbia University Medical Center (CUMC) - suggests children born to mothers who smoke while pregnant may be more likely to develop schizophrenia.
The researchers recently published their findings in the American Journal of Psychiatry.
Schizophrenia risk 38 percent higher for offspring of smoking mothers
To reach their conclusion, the researchers analyzed national registry data of all live births that occurred in Finland between 1983-1998, identifying 977 cases of schizophrenia among offspring.
These schizophrenia cases were matched by sex, date of birth, and residence to children without schizophrenia.
The mothers of the children in both groups provided blood samples in the first trimester and early second trimester of pregnancy, and these were analyzed for the presence of cotinine - a biomarker of nicotine, used to determine exposure to tobacco smoke.
The researchers found that a higher level of cotinine in the blood samples of expectant mothers was associated with a greater risk of schizophrenia among offspring.
Compared with offspring born to mothers who had low nicotine exposure during pregnancy, those born to mothers with heavy nicotine exposure during pregnancy were 38 percent more likely to develop schizophrenia, the team reports.
According to the authors, their study is the first to investigate the association between a biomarker of maternal smoking and risk of schizophrenia among offspring. They add:
"It provides the most definitive evidence to date that smoking during pregnancy is associated with schizophrenia. If replicated, these findings suggest that preventing smoking during pregnancy may decrease the incidence of schizophrenia."
Dr. Brown says their results highlight the importance of educating the public on the potential health risks that smoking during pregnancy may have for a child's long-term health.
He notes that future research on maternal smoking should focus on identifying the biological mechanisms that underlie such health risks.
"Finally, it is of interest to examine maternal cotinine in relation to bipolar disorder, autism, and other psychiatric disorders," adds Dr. Brown.