Background: Women have described normal labour and birth in terms of their emotions. Major advances in knowledge have occurred within the sciences resulting in an understanding of emotions as prime directors of human behaviour which is orchestrated by neurohormones. Method: This paper focusses on key aspects of contemporary knowledge of childbirth physiology, neuroscience and behaviour. It integrates this understanding with women's descriptions of their emotions during labour. Findings: Neurohormones associated with labour and birth are designed to trigger a transformation in the body and behaviour and create an environment which supports both the mother and the baby. Hormones and emotions are intertwined and interconnected. Labour hormones are linked to the woman's emotions and behaviour during labour and birth as well as the physical signs of labour. An interactive model is presented which explains labour in terms of both the physical effects and the emotional affects that women have described as part of their labour experience. The hypothesis for this model is that the hormones that initiate and sustain labour also cause the instinctual emotions that women feel, and the behaviour they exhibit, during spontaneous labour and birth. Conclusions: Hormonal changes are necessary to support the physical and emotional changes during labour and birth. The neurohormones which operate during pregnancy and during labour and birth also support