Children of mothers who had bacterial infections during pregnancy are more likely to develop mental health conditions like schizophrenia and bipolar disorder.
We already knew that exposure to viruses in the womb increases a child鈥檚 risk of developing schizophrenia, but the effects of bacterial infections have been less clear.
Younga Lee at Brown University in Rhode Island and her colleagues studied 15,000 US adults whose mothers had regular health checks during pregnancy in the 1950s and 60s.
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They found that those whose mothers had urinary tract infections, bacterial vaginosis, pneumonia or other bacterial infections during pregnancy were 1.8 times more likely to one day experience psychotic conditions聽鈥� mental health conditions that can involve hallucinations or delusions 鈥� than those whose mothers had not had these infections.
Male susceptibility
The risk was higher for males and more severe infections. Men whose mothers had severe infections like sepsis during pregnancy were five times as likely to develop a condition like schizophrenia.
It isn鈥檛 clear why males seem to be more susceptible, but some evidence suggests that the placentas of female fetuses are better at buffering against environmental pressures than those of male fetuses, says Lee.
The findings are consistent with some studies in animals that have found that when pregnant females are infected with bacteria, pieces of the bacterial cell walls can cross the placenta and enter the brain of a fetus, causing structural abnormalities.
However, while bacterial infections are common during pregnancy, affecting about one in four pregnant women, conditions involving psychosis are rare, affecting less than 1 in 100 people. Prenatal bacterial infections probably only cause such conditions when there is an underlying genetic susceptibility, says Lee.
鈥淏ased on this and other research, we think that the best thing we can do is to carefully monitor women whose offspring are at genetic risk for schizophrenia, and to keep their pregnancies as healthy as possible,鈥� says Lee. Bacterial infections in these women should be swiftly treated with appropriate antibiotics, she says.
American Journal of Psychiatry
