Some anti-vaccine activists believe that if pregnant women are vaccinated, their children will later develop autism. However, more and more studies have proved that vaccines do not cause autism.
A recent study found that the fact may be the opposite of what anti-vaccine people think-pregnant women may need vaccines to prevent infection during pregnancy in order to prevent their children from suffering from autism.
A recent paper published in the Journal of Neurology (JAMA Psychiatry) of the Journal of the American Medical Association said: If a pregnant woman is infected during pregnancy, then the risk of autism and depression will be higher for the child. 
The study analyzed all children born in Sweden between January 1973 and December 2014, totaling nearly 1.8 million children, of which 48.6% were women and 51.4% were men. By 2014, the oldest ” child” in the study will be 41 years old.
Since Swedish medical birth registration is linked to the national hospitalization registration, researchers can integrate the diagnosis of mother’s infection in hospital with the child’s birth registration for research.
Similarly, through the information of hospitalization registration, researchers can also detect the mental health status of children after birth.
In order to assess the risk of infection during pregnancy to the child’s mental and pathological state, the researchers established a corresponding risk model.
The results showed that if pregnant women were diagnosed with infection and received hospital treatment during pregnancy, the risk of children going to hospital for treatment due to autism and depression increased significantly, and the risk of suicide of children was higher as adults.
The risk ratio (HRS) derived from the model shows that if the child has been infected during pregnancy, the risk of autism and depression will increase by 79% and 24% respectively.
This is an increase in relative risks. For individuals, the absolute risks of depression and autism are still small. However, in the large-scale population, the number of cases caused has increased considerably.
In addition to autism and depression, researchers also studied bipolar disorder and insanity (including schizophrenia). However, the results showed that the risk of bipolar disorder and insanity did not increase significantly after the mother contracted the infection during pregnancy.
Do different types of infection produce different risks?
Is the severity of the mother’s infection during pregnancy related to the risk of the child’s illness? Can the mother suffer from less severe infection during pregnancy, and the child’s risk of autism or depression will be less?
In response, the researchers classified the collected records according to severe or mild infection. For heavier infections, there are septicemia, influenza, pneumonia, meningitis, chorioamnionitis, etc., while for lighter infections, there are common urinary tract infections in female population.
The results of the study found that regardless of whether the mother is seriously infected or slightly infected during pregnancy, the risk of disease in the child is almost the same. Even if the mother only suffers from mild urinary tract infection during pregnancy, the risk of autism and depression is still higher.
In other words, it is not a specific pathogen that damages the brain of the fetus, but almost all infections cause problems.
Some other studies have found that if urinary tract infection occurs during pregnancy, the risk of fetal morbidity and stunting will increase. However, urinary tract infection may also be a symptom of some more serious infections (such as pyelonephritis). Therefore, the author believes that further research is needed to quantify the impact of urinary tract infection inflammation on the fetus in pregnant women’s bellies.
Why does the infection of pregnant women bring these risks to the fetus?
This is only an observational study, it only finds out the significant relationship between the two and does not further explain how infection during pregnancy affects the development of fetal brain. However, other studies have found that infection in pregnant women can cause inflammatory reactions, and some inflammatory proteins can affect gene expression in fetal brain cells. Other studies have shown that maternal inflammation promotes the production of the neurotransmitter serotonin in the placenta, which may affect fetal brain development. 
Although the study has some limitations, for example, the study is limited to Swedish women. For another example, it may be genetic susceptibility that causes both mother’s susceptibility to infection and child’s increased risk of mental illness. However, there is such a significant link between infection during pregnancy and the risk of autism and depression in children, which is still worthy of vigilance.
” Although individual risks look low, the impact may be significant from a demographic perspective,” the paper concluded. For this finding, the author emphasized the importance of avoiding infection during pregnancy, and suggested paying attention to prevention of infection and anti-inflammatory treatment.
” The research results show that infection should be prevented as much as possible during pregnancy, for example, influenza vaccination should be called for during pregnancy,” said Verena Sengpie, associate professor and author of the paper at the Faculty of Obstetrics and Gynecology of Gothenburg University in Sweden. 
The health condition in these nine months may be related to the life-long happiness of mother and child.
- al-Haddad, B. J., Jacobsson, B., Chabra, S., Modzelewska, D., Olson, E. M., Bernier, R., … & Waldorf, K. M. A. (2019). Long-term Risk of Neuropsychiatric Disease After Exposure to Infection In Utero. JAMA psychiatry.
- Child’s elevated mental ill-health risk if mother treated for infection during pregnancy . https://www.gu.se/english/about_the_university/ news-calendar/News_detail//child-s-elevated-mental-ill-health-risk-if-mother-treated-for-infection-during-pregnancy.cid1619697
CARLY CASSELLA. Major Study Finds Pregnancy Issue Actually Linked to Autism, And It’s Not Vaccines.