Certain maternal pregnancy complications are associated with an increased risk for schizophrenia spectrum psychoses among individuals at high genetic risk for the condition, Finnish research shows.
The team found that maternal hypertension and infections during pregnancy, as well as placental abnormalities, significantly predict the development of schizophrenia spectrum psychoses in individuals with a maternal history of psychosis.
"These results underline the role of the prenatal period in the development of schizophrenia spectrum disorders and the importance of careful monitoring of the pregnancies of mothers with psychotic disorders," say Janna Suvisaari (National Institute for Health and Welfare, Helsinki) and team.
The findings come from a study of 271 individuals born to mothers with a history of schizophrenia spectrum psychosis and 242 individuals born to mentally healthy women between 1941 and 1977.
Over a mean follow-up period of 40 years, 29 high-risk individuals developed schizophrenia spectrum psychosis (schizophrenia [n=19], schizoaffective disorder [n=5], delusional disorder [n=1], and psychotic disorder not otherwise specified [n=4]).
Overall, there were no differences in maternal obstetric complication rates between high-risk patients and controls, although the 1-minute Apgar score was lower in the high-risk group and their mothers were more likely to have had previous miscarriages than those of controls.
However, among high-risk individuals, maternal hypertension during pregnancy, maternal infections during pregnancy, and placental abnormalities were significantly associated with an increased risk for developing schizophrenia spectrum psychosis, at odds ratios (ORs) of 4.1, 3.7, and 4.1, respectively.
Furthermore, each 1 mmHg increase in maternal diastolic blood pressure during pregnancy was associated with a 1.042-fold increase in the hazard rate ratio for other mental health disorders in the high-risk group.
Suvisaari and team conclude in Schizophrenia Bulletin: "Common medical problems during pregnancy ‑ infections and hypertension ‑ and not labor-related factors were associated with increased risk of schizophrenia spectrum psychoses in the offspring of mothers with schizophrenia spectrum psychoses."
They add: "The complications that predicted future development of schizophrenia spectrum psychoses in the HR group were not more common in HR versus control mothers, suggesting that the finding was not explained by a gene‑environment correlation."
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