Does maternal body mass index during pregnancy influence risk of schizophrenia in the adult offspring?

Maternal obesity in pregnancy has been linked with several adverse outcomes in offspring including schizophrenia. The rising prevalence of obesity may contribute to an increase in the number of schizophrenia cases in the near future; therefore, it warrants further exploration. We reviewed current evidence regarding maternal body mass index (BMI) in pregnancy and risk of schizophrenia in adult offspring. We searched PubMed and Embase databases and included studies that were based on large and representative population-based datasets. A qualitative review was undertaken due to heterogeneity between studies. Four studies with 305 cases of schizophrenia and 24,442 controls were included. Maternal obesity (pre-pregnant BMI over 29 or 30 compared with mothers with low or average BMI) was associated with two- to threefold increased risk of schizophrenia in the adult offspring in two birth cohorts. High maternal BMI at both early and late pregnancy also increased risk of schizophrenia in the offspring. Discrepant findings from one study could be attributable to sample characteristics and other factors. The area needs more research. Future studies should take into account obstetric complications, diabetes, maternal infections and immune responses that might potentially mediate this association.