(Ivanhoe Newswire) -- A new study shows first-time mothers are at the greatest risk of developing psychosis in the month following the birth of their child even if they have never been hospitalized for mental illness.

Researchers at the Karolinska Institutet in Stockholm conducted the study. They looked at first-time mother data collected between 1993 and 2000. The scientists found 1.2 cases for every 1,000 births involved a mother who had been admitted to a hospital for psychosis within 90 days of giving birth. Researchers also established the risk of psychosis increased with maternal age.