Collier F, et al. - Using linear regression, researchers examined the link between perinatal factors (gestation, labour, sex, birth size), naïve Treg (nTreg) over the first postnatal year, and development of food allergy in a birth cohort (n=1074). At birth (n=463), six (n=600) and twelve (n=675) months, they assessed the proportion of nTreg in the CD4+ T-cell compartment by means of flow cytometry. At one year, food challenge was used to determine IgE-mediated food allergy. The proportion present during infancy was mainly determined by the proportion of nTreg at birth, this indicated the significance of prenatal immune development. A transient decrease nTreg was observed in relation to exposure to labour vs delivery by pre-labour Caesarean section. Decreased nTreg at birth were detected in infants that developed food allergy. Also, infants with subsequent food allergy more evidently exhibited labour-associated decrease in nTreg at birth.