Caesarean section and instrumental delivery rates are increasing in many parts of the world due to a range of cultural and medical reasons, with limited consideration as to how 'mode of delivery' may impact on childhood and long-term health. However, babies born particularly by pre-labour caesarean section appear to have a subtly different physiology to those born by normal vaginal delivery, with both acute and chronic complications such as respiratory and other morbidities being apparent. It has been hypothesised that inherent mechanisms within the process of labour and vaginal delivery, far from being a passive mechanical process by which the fetus and placenta are expelled from the birth canal, may trigger certain protective developmental processes permissive for normal immunological and physiological development of the fetus postnatally. Traditionally the primary candidate mechanism has been the hormonal surges or stress response associated with labour and vaginal delivery, but there is increasing awareness that transfer of the maternal microbiome to the infant during parturition and transgenerational transmission of disease traits through epigenetics are also important. Interventions such as probiotics, neonatal gut seeding and different approaches to clinical care have potential to influence parturition physiology and improve outcomes for infants. This article is protected by copyright. All rights reserved.