Smoking cigarettes while pregnant — or just in general — is never good for your health.
There have been countless studies linking pregnancy and nicotine and other carcinogens found in cigarettes to higher risk of birth defects, miscarriages and premature births among other serious problems.
But one study suggests that, unlike previously thought, there may not be a link between smoking and the child developing schizophrenia and bipolar disorder later in life.
The study, published in the journal JAMA Psychiatry, looked at data from 1.7 million people born in Sweden in the 1980s and 1990s. The researchers compared the rate of schizophrenia and bipolar disorder. At first, the researchers found that children who were born to women who smoked had a 25 to 51 percent higher rate of developing a severe mental illness compared to children born to mothers who did not smoke during pregnancy.
However, when the researchers considered other factors that could have contributed to mental illness, the connection between smoking and severe mental illness was no longer strong. To verify those other factors, the researchers compared siblings whose mothers smoked during one pregnancy and not the other. This was done in order to control for genetic and environmental factors that may contribute to mental illness.
Their analysis did not show a large difference in the rate of mental illness in those siblings, suggesting that smoking while pregnant may not cause the child to develop mental illness later in life.
“We found that the association is likely explained by other factors, rather than anything specific to exposure to smoking during pregnancy,” said study author Patrick Quinn, a postdoctoral fellow in the department of Psychological and Brain Sciences at Indiana University.
Although these findings suggest that maternal smoking does not cause severe mental illness for the child, Quinn stresses the fact that smoking is still a dangerous risk for a growing fetus.
“None of these findings say that there is anything safe about smoking during pregnancy,” Quinn says.
In fact, the study did support previous findings that maternal smoking can contribute to low birth weight and premature births, which increase the risk for other health-related issues later in life.
The study also emphasized that there are a variety of factors that increase the risk of severe mental illness, and further research is still needed in order to identify those factors.