Physiological changes in the postnatal mother
During labour and delivery, there is inevitably some loss of blood and other body fluids (for example, from vomiting and sweating), which is tolerable by the majority of women. Some degree of this is normal. Additionally, most women in labour remain for long hours without taking food or sufficient fluids, which can leave them dehydrated. Unless they are rehydrated quickly after the birth, physiological complications become more likely.
During pregnancy, activity in almost all the mother's body systems changes, including the heart, lungs, blood volume and blood contents, reproductive system, breasts, immune system and hormones. In the postnatal period, all these dynamic body systems have to adjust from the pregnant state back to the pre-pregnant state, and there is a potential risk of complications as these adjustments occur. Common examples are breast infections and deep vein thrombosis (blood clots in the veins of the legs). The period in which these physiological adjustments take place in the postnatal mother is called the puerperium.
Additionally, labour is a painful experience for most women, particularly for those giving birth for the first time. There is also tension and anxiety about the outcome of labour and delivery. Having a baby is a joy, but it can also be a source of worry. Women in the postnatal period are often coping with stressful conditions and thus they need sustained psychological support.