The new findings, however, add to this knowledge by revealing that infection in general during pregnancy, too — including when the actual infectious agent does not reach the fetal brain — is linked to a greater risk of the child developing autism or depression later in life.

The researchers studied data on all children, totaling almost 1.8 million, born in Sweden during the years 1973-2014. The particulars from the Swedish Medical Birth Register were linked to the national inpatient register, which records whether the mother was treated in hospital with an infection diagnosis during pregnancy.

Using the inpatient register, the researchers also monitored these children’s mental health until 2014, when the oldest were aged 41.