['The effect of labour and different labour-related factors on the cord blood (CB) cell cytokine production is still relatively unknown.', 'To study the relationships between the production of IL-5, IL-10 and IFN-γ in CB samples and maternal, early neonatal and birth-related factors.', 'Whole-blood samples were collected after birth (n=423) and they were stimulated for 24 and 48 h with a combination of phorbol ester and ionomycin. Production of IL-5, IL-10 and IFN-γ was determined using ELISA. Maternal, early neonatal and birth-related variables were recorded prospectively during pregnancy, and during and after delivery.', 'After multivariable adjustment for confounders, the strongest predictor of IL-5, IL-10 and IFN-γ production in CB cell samples was the season of birth. Children born in the spring had significantly lower cytokine responses compared with those born in the fall. IL-5 production was inversely associated with female gender of the child and maternal smoking. If corrections for white blood cell (WBC) counts were not performed, IL-5 production was also significantly associated with the mode of delivery. Respectively, the production of IL-10 and IFN-γ was inversely associated with prostaglandin induction before birth.'] Is production of interleukin-5 , -10 and interferon-γ in cord blood strongly associated with the season of birth?