Children born by cesarean section (“c-birth”) are known to have different microbiota and a natural history of different disorders including allergy, asthma and overweight compared to vaginally born (“v-birth”) children. C-birth is not known to increase the risk of schizophrenia (SZ), but to be associated with an earlier age at onset. To further explore possible links between c-birth and SZ, we compared clinical and biological characteristics of c-born SZ patients compared to v-born ones.

Four hundred and fifty-four stable community-dwelling SZ patients (mean age = 32.4 years, 75.8% male gender) were systematically included in the multicentre network of FondaMental Expert Center for schizophrenia (FACE-SZ).

Overall, 49 patients (10.8%) were c-born. These patients had a mean age at schizophrenia onset of 21.9 ± 6.7 years, a mean duration of illness of 10.5 ± 8.7 years and a mean PANSS total score of 70.9 ± 18.7. None of these variables was significantly associated with c-birth. Multivariate analysis showed that c-birth remained associated with lower peripheral inflammation (aOR = 0.07; 95% CI 0.009–0.555, P = 0.012) and lower premorbid ability (aOR = 0.945; 95% CI 0.898–0.994, P = 0.03) independently of age, age at illness onset, sex, education level, psychotic and mood symptomatology, antipsychotic treatment, tobacco consumption, birth weight and mothers suffering from schizophrenia or bipolar disorder.

Altogether, literature data as well as our results suggest that c-birth is associated with lower weight gain and lower inflammation in schizophrenia, which could be explained by microbiota differences. Further studies should take into account c-birth when exploring the role of microbiota in SZ patients.

The authors have not supplied their declaration of competing interest.