The type of delivery and antipsychotic medications could modulate clinical features of schizophrenia and nicotine dependence by affecting gut microbiota composition. In this study, we aimed to investigate whether the age of disease onset, severity of PANSS (Positive and Negative Syndrome Scale) psychopathology and nicotine dependence might be associated with the type of delivery among two groups of patients with schizophrenia without antipsychotic therapy: first-episode patients, and chronic patients, non-adherent to antipsychotic medications. Information regarding antipsychotic non-adherence, smoking status, and the type of delivery (vaginal delivery or caesarean delivery) was obtained from autoanamnestic and heteroanamnestic data. Age of disease onset was defined as age at the patient’s first hospital admission due to a psychotic episode at which the diagnosis of schizophrenia was used. PANSS evaluation data was taken during the acute state of the illness at the most recent hospitalization. Values of the age of disease onset, PANSS score and PANSS factor and prevalence of early (≤ 26 years) and late (> 26 years) disease onset did not differ significantly between patients born by caesarean delivery and vaginal delivery (p > 0.05). The prevalence of smokers was significantly higher among patients born by caesarean delivery (p = 0.012). The caesarean delivery is associated with ~9%-fold greater risk of nicotine dependence. We did not find any associations of the age of disease onset and PANSS psychopathology with the type of delivery among patients without therapy, but our results implicate that caesarean delivery might be a risk factor for nicotine dependence in that patient group.